If you want official clarification, you should contact support.  Keep in mind that the forum is answered by the community, and the admin rarely reads or responds to posts.

That being said...

I don't see any NSFW games index that offer paid content. If you do see one, it's either not indexed correctly or it's mislabeled. In that case, you should report it using the button at the bottom of the game's page. I just want to remind you that Itch removed those games from its search engine, but so far, they haven't been removed from the Itch payment system; those are two different things.

Itch.io uses an automated system as its first line of defense to determine whether a game should be indexed or requires manual review.  This means that not all games are reviewed by a human, and therefore, errors can occur.  There are games that should be indexed but aren't, and vice versa.

Due to the issues with NSFW payment providers, the staff has been under even more strain than usual, and response times are much longer.  So, you should also expect longer wait times when reporting a game or requesting that it be re-indexed.

If you see a game that violates the law or Itch.io's Terms of Service, it's almost certainly an error by the automated system, and the best thing to do is report it so it can be reviewed by a human. But remember that Itch.io is a self-publishing platform, and Itch.io rarely deletes games.  What they usually do is unlist the game or remove it from their payment platform.  Also, remember that on Itch.io you can use the "Direct to You" option, meaning that the sale of the game is not processed through Itch.io, but directly by you. If PayPal detects that you are violating their Terms of Service, they will likely suspend your account.