I think the context we are referring to here is really free speech. Should we tolerate speech (opinions) that we despise or disagree with? Absolutely. And here we have the attackers responding to feeling insulted (framed as 'intolerance') by not being accepted/agreed with. Then they respond in kind and no progress is made.
You show me those people responding to equal/higher hostility and I guarantee I can show just as many examples of the opposite. And what I mean there is not "you're side is worse," I mean there are aggressive and horrible actors on both sides, who should not be the frame of reference for debate. But too often they are, and too often examples of hostility as used as an excuse for escalation or to avoid real debate.
indeed, responding to, say, right-wing intolerance of trans people, by not tolerating it, is totally okay, despite your FUD, for reasons described by Popper
don't like your own intolerance of e.g. trans people, and actual attacks on them, to be responded to? maybe keep your intolerance and actual attacks to yourself, problem solved
in other words, it's a reaction to intolerance, specifically a decision not to tolerate intolerance - as we covered before, we don't need to, since doing so will end tolerance entirely (see Popper's paradox of tolerance for this)