A lot of the left isn't "liberals" any longer--they're quite notably illiberal--and that portion of the left hates bullies so much that they're willing to be much bigger bullies to anyone who questions how badly to bully the perceived bullies.

For instance, on Medium you routinely see people with moderate leftist views being called all sorts of vile things because they, for example, ask for evidence before leaping to a conclusion.

Leftists are now the ones leading the charge for professors to be fired despite tenure for speaking the wrong opinions (c.f. Amy Wax). Yes, the opinion contained a bit of genuinely racist stuff, but the actually liberal position is that you counter speech with speech and she might be disgraced but doesn't need to worry about being fired (i.e. there is some idea of proportionality of how to react to bullies).

This is the same kind of reactionary ugliness that has taken hold of some of the right, and the same sort of dehumanization that has presaged some of the worst atrocities in human history. Thus, to read "liberals just don't like bullies" as "the left just doesn't like bullies" drastically understates an immense problem on the left. (Not actual liberals.)