There is no basis in the law for the premise that Muslim aliens can’t be temporarily banned from entry. Section 1182(f) of the United States Code makes it clear that the president would be within his authority in doing so. Depending on how the presidential order was written and given it may or may not pass subsequent tests of constitutionality, but it clearly passes a threshold test of minimum basis in the Constitution and the written law.
There is no basis in history for the premise that Muslim aliens can’t be entry. Groups expelling each other from their countries is a routine historical occurrence.
The basis in realpolitik and foreign diplomacy is shaky. Under normal circumstances we should be concerned that restricting the movement of foreigners would result in similar treatment of our citizens abroad. But it can’t get much worse for Americans, for example, in many areas in the Middle East. Even if they were restricted temporarily from all Middle Eastern countries, the net result probably would be positive.
Even if there were a basis in morality and ethics that trumped (heh) our own security concerns, I would never accept it from a liberal. At least in the local island nation that is Nathan Wyatt, liberals and progressives have lost their privileges. Their poor record with regard to authentic tolerance and open debate is well-established, and they habitually promote the worst elements both in society generally and the marketplace of ideas in particular. Trump is Hitler, they say, and they’ve been saying similarly erratic and extreme things as long as I’ve been paying attention. There is no reason to heed their cries of, “Wolf!”