If he does it again, I hope it's on an airplane. Let him cool his heels awhile.
In the United States he can make threats anytime, anywhere, and to whom anyone he pleases and the authorities will take no action against him. Why? Because he is a muslim.
As far as the people who are supposed to enforce the law are concerned being a muslim gives one more immunity from the laws than being an illegal alien does.
In both cases, only the laws that benefit them apply.