In my opinion, you should need the consent of the people who the faces are trained on. AI does not operate in a vacuum, it has to look at many faces to learn how to generate a face, and this would likely put it under the provisions of Section 2252.
It would be illegal either way, even if it were somehow trained off adult faces and modified (I dont think this possible), because it fails the “indistinguishable from a real minor” test. If someone were to use StyleGAN to flood the internet with fake imagery and drive CP producers out of business, I can’t say I would care, even if it were trained off real people, although I would avoid that legal hazard.
Driving CP producers out of business would be very difficult. In an article in RT, a Dutch man paid as little as $25 to $50 to order someone to perform acts on camera live. Unfortunately, people in third world countries are very poor and very desperate.