But the "ideological exclusions were not "relics of the McCarthy era." 

They originated from the Alien Registration Act of 1940, signed into law by President Roosevelt as a national security measure on the eve of World War II. The bill make it a federal crime for anyone to 'knowingly or willfully advocate, abet, advise or teach the duty, necessity, desirability or propriety of overthrowing the Government of the United States or any State by force or violence, or for anyone to organize any association which teaches, advises or encourages such an overthrow, or for anyone to become a member of or to affiliate with such an association.'

Roosevelt and all that fought and died in World War II should be spinning in their graves at the sight of all those that today are, with impunity, aiding and abetting, teaching, advising, advocating and all the rest. As I posted before, there were traitors and their abettors abroad in the United States prior to and during World War II that President Roosevelt had to neutralize as outlined by  Michelle Malkin  in In Defense of Internment.  Unfortunately innocents were caught up in the dragnet and suffered relocation and other humiliations because of the real actions of a few. It might surprise some to know of the existences of the 2006 version of the camps, "just in case."

Why was Frank so passionate about "removing ideological exclusions?" The reasons may surprise you. 

“I was in an ideal situation because while I was in favor of the overall bill, I cared most of all about the exclusions, and I was prepared to try to defeat the bill if I was not successful in reforming what I considered to be the most outrageous aspect of American immigration law, the antigay, anti-free-speech McCarthyite hangover,” said Frank. 

To Frank, the ideological exclusions were inconsistent with the notion of free speech. But the question was: Should the full First Amendment right to free speech be extended to non-U.S. citizens while they were in America? Frank said yes. He then flipped the issue on its head by arguing that denying entry to foreigners with subversive or “dangerous” views and radical ideologies was a de facto violation of American citizens' First Amendment rights to hear those views. 

“Beginning around the turn of the century,” said Frank, “American law contained a large number of exclusions to protect what legislators apparently thought was a fragile citizenry from all manner of dangerous foreign influences. Anarchists, people who believed in polygamy, Communists, people who knew people who were related to Communists, people who thought and said unpleasant things about America – the list of those kept out of America was egregious and in total violation of the spirit of free expression.”

As DiPippo says: 

Is is typical for left-wing politicians to waltz past the bones of Communism's 150 million victims on their way to trivialize the dangers that radical ideologues present. Frank is no exception, since he considers foreigners who hold totalitarian views to be of no concern to national security, a view he has held since at least 1981, the year he officially began working to eliminate ideological exclusions. The Soviet Union, America’s long-time communist enemy, did not collapse until 1990. Though Frank’s final exclusion amendment included language making deportable “any alien who participated in Nazi persecution,” there was no clause barring any alien who participated in Communist persecution.

When Frank’s exclusion amendment became law, it said aliens could not be excluded or deported “because of any past, current, or expected beliefs, statements, or associations which, if engaged in by a United States citizen in the United States, would be protected under the Constitution of the United States.” 

Frank used the elimination of ideological exclusions to facilitate the removal of another long-standing exclusion statute, one truly unjust. It is important to mention this since it raises questions concerning his motives for legislating against ideological exclusion in the first place.

According to DiPippo, here's the reason why Frank was so adamant about removing any "exclusion of ideology." 

Frank tailored his attack on ideological exclusions to expedite the removal of the sexual preference exclusion, an exclusion that denied homosexual immigrants entry to the U.S. Given the cultural climate of the 1980s, a stand-alone effort to have the sexual preference exclusion removed would not have been supported by many Congressmen, regardless of their private views on homosexuality. So in a brilliant legislative sleight-of-hand, Frank crafted the comprehensive immigration exclusion amendment to define the only reasons that entry to America could be denied – and he left the sexual preference exclusion out. 

That strategy of omission put anyone wanting to continue the ban on admitting homosexual immigrants in the unsavory position of having to sponsor a separate amendment seeking to continue that ban. In his essay “A Case Study in the Effective Use of the Political Process,” Frank explains his strategy: 

My intention was to take the legitimate bases for excluding people from this country – namely, that they would in some real way be dangerous to our well-being – and embody them in a new section that would replace the existing obnoxious [ideological exclusion] sections. I would deal with the anti-gay exclusion simply by leaving it out of the re-draft. Thus, no separate vote would be taken on whether or not to repeal this provision, because its abolition would be accomplished by omission. And since I was part of the majority that would be presenting the new bill, the burden in Congress would thus be shifted to those who sought to preserve this homophobic aspect. 

In other words, Frank took an issue concerning national security and parlayed it into a significant victory for gay rights.

That's right. Frank wrote legislation that has put the United States in physical and ideological peril in order to promote gay rights. 

In 1987, over the objections of the State Department because of security concerns, Frank’s exclusion amendment was made temporary law. Though President Reagan also objected to Frank’s ideological exclusions amendment, he accepted it in compromise to get broader aspects of the McCarran-Walters revamp passed into law. For the first time in American history, the full First Amendment right to free speech and free association, once exclusively enjoyed by full U.S. citizens, had been granted to non-citizens and visitors to the United States. The moment Barney Frank’s exclusions amendment was made law, it became unlawful, on the basis of their beliefs alone, to deny entry to immigrants or other foreign nationals with radical ideologies. It also made it nearly impossible to deport them once they were here. 

Three years later, the overhaul of McCarran-Walter was finished, and it became law as the Immigration and Nationality Act of 1990. Frank’s ideological exclusions amendment remained intact, except for a single word. The final amendment said that an alien could not be excluded from entry into the U.S. nor deported once there ''because of any past, current or expected beliefs, statements or associations which, if engaged in by a United States citizen in the United States, would be protected under the Constitution.” Frank had also wanted to prevent the U.S. from denying entry to immigrants based on past “activities,” but under pressure from the Bush State Department, Frank was forced to drop “activities” from the amendment’s final wording.

And the New Duranty Times (a.k.a., New York Times) 

"vigorously supported Frank and his fellow Democrats' drive to remove ideological exclusions, reporting on its permanent removal on Oct. 26, 1990: "Representative Barney Frank, the Massachusetts Democrat who was the chief House negotiator in the conference committee, said the new provisions worked out Wednesday night and today 'made rational the reasons a person can be excluded,'and added, 'We are saying you can't exclude someone because of their speech, their beliefs, or their associations.' [Emphasis added by DiPippo.]

Some changes were made in 1990 and 1996, "but Frank's ideological exclusions amendment remained untouched and in force until after the 9/11 attack. 

The 1996 exclusion list allowed immigration officials to bar aliens from entry or deport them for the following terrorism-related reasons: 

(1) has engaged in a terrorist activity,

(2) a consular officer or the Attorney General knows, or has reasonable ground to believe, is engaged in or is likely to engage after entry in any terrorist activity .

(3) has, under circumstances indicating an intention to cause death or serious bodily harm, incited terrorist activity,

(4) is a representative of a foreign terrorist organization, as designated by the Secretary under section 219, or

(5) is a member of a foreign terrorist organization, as designated by the Secretary under section 219, which the alien knows or should have known is a terrorist organization is inadmissible.

But U.S. immigration officials could not deny entry to or deport aliens solely on the basis of their political or ideological beliefs or the associations they engaged in while in America. And the remaining exclusions, as they related to terrorism, were filled with ambiguities that monkey-wrenched the process of deporting suspect aliens expeditiously. The Center for Constitutional Rights, National Lawyers Guild, and other left-wing groups lined up to exploit those ambiguities. They filed endless litigation in defense of aliens arrested for suspicion of involvement in crime, terrorism or terrorist-related activity.

James R. Edwards  of the Hudson Institute sums it up in this article at the Center for Immigration Studies. 

Teddy's Terror Loophole