Really great comprehensive article on the history of "political correctness" and how the phrase itself transformed from a mild chiding used among progressives ironically into an insidious tool used by the right to actually co-opt otherwise left-leaning people. Hmm. Sounds familiar.
To play the anti-political-correctness card in response to a legitimate question about policy is to shut down discussion in much the same way that opponents of political correctness have long accused liberals and leftists of doing. It is a way of sidestepping debate by declaring that the topic is so trivial or so contrary to common sense that it is pointless to discuss it. The impulse is authoritarian. And by presenting himself as the champion of common sense, Trump gives himself permission to bypass politics altogether.
Extremely relevant to this thread.