Come on, we’re talking about a recreational fanfiction exchange. Being able to participate is not a life or death matter. This is a situation where “because you’ve acted in a way reasonable people find abhorrent and no one wants to hang out with you” is a perfectly acceptable reason to kick someone out. It’s not like they’re ever going to be able to make rules to cover every situation—should mods just sit on their hands if a situation arises they’ve never considered?