Good point.
I think a good way to vet the “refugees” would be to stick them in a waiting room for a few hours. Let them get relaxed and have a double mirror or camera for observation. This waiting room has a TV with a fake, pre-recorded news show and one of the segments is about 9/11. Show the plane flying into the twin tower(s), people jumping to their death etc and watch their reaction. Video of muslims attacking Christians would work as well.
Another option would be to put sensors on them that measure emotions and show the same clip(s).
Elation, happiness etc. No deal. Sadness, ok.