I don't necessarily disagree with you. But I would note two things:
1. Upon what standard is this "unambiguously, morally wrong"? Strong language.
2. Secondly, the standard to which I would appeal is the law of God (in the Judeo-Christian sense) as seen through and applied by the teaching of Christ and his apostles (i.e., NT ethic). Upon that standard love of neighbor is a moral imperative of highest order. Yet, love of neighbor, can be argued for the refugee, the foreigner, the sojourner, etc., and next door neighbor and family. And so, I think we should debate to what extent we should go to protect our neighbors from those who might be seeking their destruction. Now of course, when you actually look at the chances we and our neighbors are actually threatened, they are infinitesimally small. And so, in my opinion, using appropriate vetting procedures, we ought to extend love to the potential neighbor and not bar immigration.
That said, I'm not sure how terrible a 90 day waiting period is actually and I would say that I do appreciate that the Trump administration versus the previous administration, isn't going to discriminate against Christian refugees. No matter the rhetoric of the previous administration, their actions effectively gave immense preference to Muslim refugees over Christian. Why give preference to either?