The parallels are tenuous at best.
It’s relatively easy to determine if someone was from Iran simply by looking at their passport. Passports were much more difficult to counterfeit then. Determining whether someone is a Muslim is much more tricky.
I suspect (though I haven’t done the research to verify) that it wasn’t simply a matter of an Iranian declaring in front of the appropriate US official that he opposed the Khomeini regime. Usually documentation is necessary for these sorts of exceptions.
The same would hold true if there were to be any Muslim exceptions. Every good Muslim knows that in order to further the advancement of Islam, lying is acceptable. One can lie about being Muslim, lie about support of Sharia, lie about support of ISIS, lie about liking Jews, etc.
Simply asking people before they are admitted to the USA if they’re Muslim and whether they support Sharia is a waste of time. Those who want to get in will lie. Knowing that they need to lie, they’ll prepare. They’ll fake a conversion to Christianity as is happening in Germany and they’ll present a nice pretty certificate of baptism as proof. They’ll claim to be atheists or agnostics and say anything we ask because Islam allows this.
The devil is in the details. IDing Muslims simply isn’t that easy if they don’t want to be IDed.
It should not be based merely on taking their word. Any recent conversions would not be accepted either. There would have to be a relationship with an existing church and vouching from there as well as other people. Fox had a report on organizations with heavily documented Christians applying to be refugees. There are solid ways to prove it and anyone who is lacking solid proof would not be accepted.