Eh, so be it. CTH made its own bed and in the thread talking about federating users are demonstrating why people should be skeptical of the value of federating with a troll-prone instance. The mods of CTH back in the day also sometimes asked their users to behave themselves, it didn’t really work. And since their admins have explicitly said they won’t police trolling elsewhere, it’s really nothing more than a passing suggestion.
In an ideal world, lemmy.world waits and sees if they’re really committed to keeping their shit on local. In a non-ideal world never federating with instances extremely likely to troll is also a pretty good choice.