The actual claim was to keep these people on that instance to make defederation easier. Which doesn't work, but AFAIK no one ever claimed to be "free speech absolutists".

That's because they're not leftists. Most of the tankies on Lemmy probably aren't. I'm sure some of them are people who get swept up in the tide of favoring mockery over patience and compassion while actually believing leftist political positions, but it's pretty clear what the bulk of them are doing.

They're corporate or authoritarian government plants trying to break the coalition of left and center. They're doing everything they can to make both look unreasonable and unhinged in the eyes of the other. Demotivating leftists from endorsing centrists who lean their way, while making centrists feel targeted and derided by the left.

It's way easier to break coalitions and sew chaos than it is to drive engagement and unity. It literally takes less thinking, less precision, and less strategy.