I hear you. But, it just seems like any minor criticism of Swift, based on talent and music, is met with over reaction. I do think some of the nasty stuff said about her on a personal level is uncalled for. But, assuming the story about Grohl's kid getting dragged by Swifties is true, I could see why he might go off half-cocked. I have no idea if what he said is true on not. If it turn out to be true then IMO, it's fair game. And, frankly, I think it's probably true that most people who put on shows like Swift do some amount of lip synching and given that Gohl is in the industry, he may be privy to information that we don't necessarily have.
Just seems like a bit of jumping the gun to assume Gohl doesn't know what he is talking about.