Fediverse

That's not radically different from what happens with other abandoned subs, except that usually they are actually abandoned and there has to be more talk about who should take over.

Reddit's policy has always been that subreddit requests only apply if someone actually goes vacant. The only reason XKCD still doesn't have holocaust denial in the sidebar is because the guy who owned the sub disappeared. The XKCD case is especially egregious because I'd argue that associating a public figure's webcomic with a horrendous opinion he doesn't hold is something that would actually open you up to a lawsuit.