It's called political correctness. There is a longstanding undercurrent in American politics of treating Constitutional rights (aka natural rights) as only applicable to Americans [0]. Framing the issue in terms of lofty universal ideals would be politically suicidal. And with the current precarious situation, giving more energy to overly-simplistic jingoist chants is not what anybody needs.

[0] this seems to be a bit of proto-fascism that helped set the stage for the overt dynamic we've now got