The only forum where this is really an issue is Miscellaneous Stuff. I would not support creating a separate PG-13/R/etc. forum, because it would concentrate and promote more such threads, rather than keeping a healthy mix as Misc does. But because this forum is for the community of a children's game, some people might expect content to be more restricted than it is.

The only thing that would, in my opinion, be appropriate would be a warning or disclaimer on the Misc forum description (like "Not all content may be suitable for children"). It's my opinion that the community members and their desires are more important to rules and policy than hypothetical child visitors. Even a disclaimer might be unnecessary if the forum rules are publicly posted, as some are now.

The web host does not prohibit explicit discussion. They allow virtually anything as long as it is legal, as most pay providers do. All additional restrictions are set by the forum and site administrators.

This poll gave some relevant public opinion. A minority of respondents supported a difference in restrictions between Jazz and non-Jazz related forums, while a majority supported fewer restrictions on sex-related discussion.