I am very curious as to what your game had to break steam's rules. It can't be the sex alone because steam legit has games like House Party which is a sex simulator...https://store.steampowered.com/app/611790/House_Party/
here is link for those that don't believe me.
Is it because you live in a country where sex games are banned on steam or did you game have like rape... or something involving minors? Also shouldn't you still be able to put a patch on itch.io?
For example, the game Requiescence by Argent Games don't have the NSFW patch on steam but put it on itch.io. That games sex scenes happen to also have a few basically rape parts... but yea even if steam may restrict indication of rape, apparently itchi.io doesn't.
It would be nice if you could explain what's stopping you from actually putting the NSFW content back up.
*update*Oh wait... i just realized you seem to be working with Y! Press Games... oh geez, I wonder if has anything to do with that... they aren't even that good of developer... two games i played from them both had awful writing and plot. just pure smut w/ good art.