> nationalist xenophobia the true most important priority for this administration

It is a little more complicated than that. It is what around 40% of American population want. (Then another 9.5% or so voted for Trump based on the price of eggs, the fact that the other candidate was a woman, and so on).

40% of the voting population*

Just because the people voted for Trump does not mean that the people don't want visa laws followed. Also, voting for someone does not give that someone carte blanche to do whatever the hell they please.