I'm not GS core dev, only a core user, and really i dislike nsfw .... But : you can open an issue on https://git.gnu.io/gnu/gnu-social/issues , make a notice to !gnusocial , send a email to the mailing list or go to irc : https://gnu.io/social/contact/. Remind to contact Other fediverse tool : Friendica have a plugin for NSFW ( Friendica have .... a lot of think)