Yes Prime Minister has a pretty funny take on this

But I think it’s important for the reason here to be that Hexbear is embarking on a project of ideological warfare.

The hexbear userbase has a tendency to attach outsize importance to their posting activities, when in reality it's just an anodyne shitposting website with general leftist politics. When a admin makes an argument to the effect "leftism is better served by you playing nicely on other instances", they're playing to tendency to try to get everyone to behave, not because hexbear can actually meaningfully engage in coordinated ideological warfare campaigns; we can't even agree with each other.

There's an old propaganda poster about carpooling during the war that works on the same conceit.

In reality, the only thing you're at risk of by federating with hexbear is the occasional post "look at what this liberal is saying on libby.world", and if that triggers a brigade, it's clearly visible due to federating tracking home instances, and can be dealt with (unlike brigading on reddit). This can (and does) even happen without federating, but you lose the biggest tool in your arsenal to actually see it while unfederated.

I'm not going to pretend to be unbiased, being a poster over on chapo.chat (or Hexbear as it's now [embarrassingly] called), but I hope those of you who support decision can at least understand how frustrating the purported justification is. The notion that hexbear has a consistent ideology to push beyond general amorphic leftism doesn't stand up to any scrutiny, so in the end the decision to defederate just comes down to "these people have opinions".