That's true, didn't know about that. However, the Coinbase Commerce has a clause that I guess (if they feel like), can apply for adult entertainment businesses.
> You agree not to use the Services in ways that:
> Are illegal, obscene, defamatory, threatening, intimidating, harassing, hateful, racially, or ethnically offensive, or instigate or encourage conduct that would be illegal, or otherwise inappropriate, including promoting violent crimes;
Depending on who you ask, "obscene" and "otherwise inappropriate" can cover adult entertainment.
Guess it's impossible for us to guess, unless a case goes to court.