Because he said it. As far as religion goes Islam is both. Religion and government. Our government needs to take up that threat possibly in a Constitutional Amendment to protect freedom for all from foreign threats related to conflicting religious freedom. If we don't recognize the threat soon we will be bound to end up like other countries with No Go Zones. Rape, beheadings, cutting off of hands, female mutilation, acid baths, honor killings. Then there is separate banking policies. No interest. Separate banking and government to conform with Sharia Law. Soon our identity as a Free Country is gone.
He was speaking about terrorists on foreign soil, not domestic. If you want to attack the man, at least do it honestly.
There's a huge gulf between civil legal limitations on aspects of Sharia law...such as banking...and banning a religious practice. Heck, I would not oppose a ban on Sharia law altogether as part of civil law...but you are calling for banning mosques and religious practice, evidently, and that can never happen in this country. If it does, it will be the end of Christianity AND of civil government. So don't conflate things like disallowing Sharia banking practices, and the banning of a religion generally...these are two utterly different things.
Again, you cannot ban a religion...and you cannot simply declare a religion to not be what it has always been in cultural and legal history. Let it go, because it will only make our fight against RADICAL Islam all the more difficult to win.