Personally, I would have no problem with the community becoming friends only if it's unmoderated membership. If I were a non member who, for example, wanted to read a fic someone linked me to, but couldn't see it and had to wait to be approved, I'd probably just go, "Fuck it" and not bother. I'd hate to see people get scared off.

Also, I think if people want their posts to be FO they'll lock it. That happened with theboysofsummer, and I didn't have to bother making the community FO (though I never planned on it anyway).

In general though, I'm not concerned with "outing". It usually dies down.