Calling an opponent a sexist or a racist are sure fire ways to ostracize them and shut them up.
It's funny how right wingers say this, in spite of them never actually shutting up, because if they didn't, there'd be no weight to their persecution complex.
It's also funny how that puts them in the same position as the people who shout racism and sexism at the drop of a hat. They both believe it will silence the opposition, but neither actually believes it does, because they're playing their designated role in their identity politics game. (Do not let their political alignment confuse you, the conservative white male is the most identity-focused out of all of them.)
And what is lost in the identity warriors' stupid race to the bottom is the fact that there is still plenty of racism and sexism left in the world. For example, Donald Trump is undeniably both. His statements are not even dog whistles, they're foghorns. And yet his supporters will pretend that pointing that out is lying, and also an attempt at censorship, because, you know, embarrassing a person for their stupidity is censorship.