Fan art of a real person has always sat on an unwritten agreement: the fan guesses what the subject would be comfortable with, and the subject finds out afterwards. Generative tools removed the friction that used to keep that guess small.
The licensed route replaces the guess with a document. The creator publishes which contexts they are happy to appear in and which depictions they will never license; a request outside that is refused with the rule it broke, rather than made and then argued about.
The output carries a manifest naming the creator, the version of their boundary set it was authorised under, and when. If the creator later narrows their boundaries, the old work is still traceable — which is what makes a revocation actionable instead of symbolic.