Follow me here:
If X wants to kill Y, X is going to figure out a way to kill Y. If Y tries to stop being killed by banning X, all that will do is induce X to look like ~X to get around the ban. Y would be much better off by discovering why X wants him/her dead and coming to terms.* If it is not possible to resolve the dispute (or if Y won't even bother to try due to prejudice), then the only rational solution is for Y to kill X first (or be prepared to die but the ban suggests Y is not up to that). So, bad as the ban is, it may only be the tip of the proverbial spear.
*What Trump should do instead of a ban, then, is to pull the U.S. military and oil interests out of the Middle East. We don't need the oil there anymore and Israel can take care of itself at this point (and we'll always have missiles, drones, aircraft carriers, and submarines if necessary). That essentially would turn Americans into Canadians in the eyes of Muslims. Americans are safe and we can redeploy our military assets or, better yet, wind them down.
Addendum 3/19/17: What was that song? "It's no fun, being an illegal alien?" Seems an understatement now.