Late reply, but it's the other way around. The payment processors don't want people charging for NSFW content, so Itch was actually recommending NSFW games should be set to free w/ no donation option, free only.
I think it's mostly blown over by now though, other than a bunch of games still being delisted temporarily (like this game).
Blowing over on Itch.
The govt's gonna fight over this like they've been on and off the last couple decades, but as for now I'm not seeing too many Itch creators getting screwed by the payment processors.
Heck, you can't even blame US politics for this thing in particular, Collective Shout is Australian.