I feel like we are having the same discussion in two different threads, but just to reply to this with a quote from another comment

And telling people that murder is okay - regardless of the rightness or wrongness of such (e.g. even if not serious but merely to lay off some steam) - seems to fall into that category?

That's probably the core of the question. People in the LW thread were advocating that jury nullification for future crimes is legal in the USA. If it is, and if there is no clear rule on DO to prevent those (as far as I've checked, there aren't, but happy to be wrong on this), there are two options

• add a rule similar to the LW one
• accept that people talk about jury nullification for future crimes

And isn’t social media supposed to be “fun”?

I would say it depends. I myself prefer casual communities, like !casualconversation@lemm.ee, !movies@lemm.ee etc. But I also know that some people are going to want to discuss "serious" topics, and that those also deserve their communities.

You might want to distinguish between AskUSA and a potential new CasualUSA, as in general, if you keep both content in AskUSA, the serious content will overwhelm the casual content.