Let's see what happens to his poll numbers.
For myself, I doubt he will be harmed. Having an idea (even a flawed one) for dealing with a problem isn't obviously worse than complacency about it (Obama).
Let us describe Trump's idea as it is: an immigration/ vacation hiatus for all Moslems while studying the problem of Moslem radicalisation, in the knowledge that ISIS has threatened to infiltrate the immigrant Moslem population with terrorists and polls suggest high levels of hostility towards the West (as well as Jews) amongst Moslem communities.
I don't find his idea altogether shocking. Just lacking in refinement - as in, the Moslem host is too imprecise to be employable. We are seeking to identify jihadists and Islamists. Even so, the primary duty of care for an American President is to protect American citizens. Vacationers and proposed immigrants are not American citizens. If you can't winnow the good from the bad, do you accept the possible cost of continuing as if there's no issue?
Maybe doing what Obama is doing "is what ISIS wants." [As if anyone knows]
The UK's Cameron has attempted to curtail Syrian immigration and this caused far less of an uproar. Indeed, there's a widespread sense that Germany's welcome to a million Syrians may destroy the EU.
At least Obama could try to address the problem. Rather than fire a volley of platitudes while pretending ISIS "has nothing to do with Islam." If your argument relies on a false premise, it is probably a poor argument.
For me, the really shocking attitude belongs to Obama. He is living in a multicultural fantasy land in which everyone is living in peace and harmony, while Moslems in London decapitate soldiers, Brussels has no-go areas, Paris has been attacked twice and an American couple murdered their coworkers at a Christmas party.
Wake up! You need a plan of action.