That's something I couldn't figure out back in the late seventies - early eighties when the Iran thing blew up. we had Iranians galore protesting and they were all in the college of engineering taking our technology. Deportation should have been the rule of the day and strict adherence to that policy. You come to this county for our services and cause trouble... you go back where you came from the same day you cause the trouble.
I'm all for tromping the " civil liberties" of these a$$holes. Maybe now that the grownups are in control, we can start doing something about it.
If not, I'm armed and ready. ;)