> stopped at all cost

Including the cost of, say, being intolerant of intolerance of intolerance?

AFAIK, one of the major reasons to be intolerant of intolerance is to prevent lynchings.

So we should start twitter mobs to stop the twitter mobs that target people currently? Or what do you mean? The only way to stop it is to teach acceptance and temperance. We didn't stop lynchings by attacking them, we stopped it by teaching people the value of tolerance for even the worst of criminals and giving them due process. It is when you refuse to tolerate criminals that lynchings occur.

This is a pretty good point. Tolerance-as-peace-treaty doesn't apply nearly as reasonably between groups as it does within a group; although that makes sense. Do not abide by the peace treaty, conflict arises; and then it's about how you resolve conflicts between groups.

Stopped at all costs means "do not engage in certain behavior, yourself, even if you think you have a good reason for it".

Even if you think the other person deserves it, because of whatever excuse that you can think of, you still shouldn't act horribly, no matter the nice sounding justification that you can trick yourself into believing.

Humans are really good at tricking themselves into believing that their horrible behavior is justified.

In this specific situation, calling someone else intolerant is just an excuse that people will use to justify their horrible behavior to others.