If you look at the popular VN list, most contain what would qualify as 'mature content' by these standards, yet they remain available without warnings. This means either: Itch.io doesn't actually share your strict mature content standards, or they're applying double standards. And we don't know where did you get the information that not all NSFW games are not indexed yet. In any case, there's clearly an issue for us here and we're trying to get help, so there's no need to show aggression to anyone (yes, we found it offensive by our standards). If you're not a member of itch staff, could you please ignore our thread? Thanks!
contains intense, potentially distressing content, including Graphic Violence (gore, blood, murder ... Disturbing Themes (cannibalism ... Some themes are subtly hinted at in the demo but fully explored in the main game. Player discretion is strongly advised.
I do not think that there is a discussion needed, if your game intends to be suitable for minors or not.
On top of that, your game is currently quarantined. This is not a new issue for games. Read here https://itch.io/t/4120453/game-quarantined-search-or-indexing-problem-read-this Read your own quarantine message for a hint why this might have happened (try downloading it while being logged out).