Wiki - The paradox of tolerance states that if a society is tolerant without limit, its ability to be tolerant is eventually ceased or destroyed by the intolerant. Karl Popper described it as the seemingly self-contradictory idea that in order to maintain a tolerant society, the society must retain the right to be intolerant of intolerance.
If you tolerate something, it is implicit you disapprove of, or disagree with, the subject requiring tolerance.
People exhibiting behavior necessitating said tolerance know this. And they don’t like any reminders that just maybe they might be really, really wrong and there are people willing challenge their behavior but are holding back.
So instead of changing their behavior, they eliminate the challenge to their behavior.