I think this is what got Yates' goat. It's a con man's ruse to figure a way to pretend you are banning a variety of nationalities in order to conceal the fact that you are banning a religion.
That just screams lack of integrity. She wasn't willing to be a participant in the Trump-Giuliani ruse. If you want to ban immigration by Moslems, draft a law that says so. And then see if it is something you can sign.
As you know, for myself, I have no problem with the religious aspects of Islam. It is the secular extensions that are concerning. Things like the imposition of religious law (No!), behavioural demands (No!), desire to impose Islam on the country of immigration (No!), tiresome claims of Moslem victimhood (No!) are the things which bother me, and doubtless many others. So if I was to draft a test, it would be all about adherence to the constitution's ideals and integration into the culture of the USA. Moslems who want these things aren't going to be a problem.