Lemmy currently has several hundred instances, and Beehaw defederated from two of them. They said in their post that they were spending a lot of time dealing with problem posts, and almost all came from those two instances.
And what's the problem? I personally think trying to make a troll -free place on the Internet is doomed to failure unless they close the whole world out, but it's their goal and I certainly support them giving it a shot.
This is all a big experiment, and it's wonderful that different approaches are being tried. We should support that, not piss on it.