I think you are right about not rushing to judgment.
I was a bit shocked when I first heard the idea of vetting Muslim Americans who are returning from abroad. But it actually makes sense. There are reports of some Muslim Americans fighting with ISIS, and others have been living abroad or extensively traveling in countries where they might have been in close contact with ISIS.
ISIS is bragging that they have planted thousands of agents around the world who are planning chemical and biological attacks. Stop and think. Who could better execute such a plan, blending into society and speaking the language, than a radicalized Muslim American who has been recruited for this purpose?
As for halting Muslim immigration, there is solid evidence coming from Europe that Muslim immigrants, particularly Sunni, do not fare well in the West due to incompatible values and attitudes towards women. As Americans we should be free to decide how many people come to our country and to impose any criteria we like without being shamed.