Why do you care if an 18+ year old who looks youthful does NSFW stuff? Take an extreme example, what if Hasbulla did nudes? He is 21 but looks extremely young. I can’t see how telling him he isn’t allowed to make nude content because of his appearance is anything other than ableist and body shaming. You don’t have to like the content or even like the people who would look at it to think the content is acceptable.

If everyone is a consenting adult then everything is fine.