I think it's worth pointing out that legality depends on jurisdiction and while it's obviously a requirement to obey the your (and other admins') local laws, it's not quite so clear-cut when it comes to other countries.
Eg. It's illegal to criticize Hong Kong's government under their National Security Law. But I think we'd (the community here, not just you and me) agree that lemmy.world has absolutely no obligation to follow that law.
I think they were hoping to lean into the uncanny valley of AI art to cause a sense of imbalance/discomfort to fit the whole secret invasion theme. And of course save a boatload of money along the way.
I'm not necessarily against it as a concept 'cause I think art will survive AI as it survived digital painting, photography, and loads of other revolutions before. But it really is kind of a slap in the face to the artists that got Marvel where it is today.