[Sharlin]

This is not a debate on who is right or wrong on the factual matters. Nobody is suggesting that the extremely rude person was factually wrong just because he was extremely rude. As you said, it's an extremely important part of public discourse that incorrectness be called out in a polite way. Nobody disagrees with that, but it's totally beside the point because here the problem was that the calling-out was anything but polite.