You don't even really need the middleman - Disney has surely uploaded pictures of Ironman to these sites so it would have them either way.

But I don't know if it's really laundered anything. If you say "Hey Meta AI, make me poster for my cookie company that has Iron man eating my cookies" I'm pretty sure Disney could still sue you. It could still sue you if you instructed a human to draw a picture that had Ironman in it so I don't even know if you need a new legal framework.