That's the paradox of tolerance for you; we must be intolerant of those that are intolerant... but you probably already know that Karl Popper theorized that [0]. Just looking around globally, we seem to be at that inflection point where this isn't mere hypothesis, but theory or law:
"Popper posited that if intolerant ideologies are allowed unchecked expression, they could exploit open society values to erode or destroy tolerance itself through authoritarian or oppressive practices."