I think calling it porn is a lawyerly overreach. Sounds like he's mostly pissed off that he wasn't compensated for a deal he had no control over, and I might be too. Just the other day I told my kid's preschool that I wasn't ok with them putting pics of my son of Facebook. They tried to dissuade my by saying that they'll have to put him aside or something when/if a photographer comes into the room. Whatever, fuck you. Kids have very little autonomy, so I think to the extent we can avoid making those sorts of choices for them, we should. I think we can all agree this isn't porn, but I don't blame the dude for trying to get a piece of the action.
He probably doesn't feel like it's porn either. Creating art with kids is all kinds of messy because most agree that they don't have agency. It's kinda funny that at one point we don't have agency, and then we do, but different kinds at different times. Ok, you can choose which parent to live with. Ok, you can now operate a boat and bag groceries for money. Ok, you can now operate a car. Ok, you can now consent to sex with some people. Ok, you can now kill someone in Afghanistan and consent to have sex with anyone. Ok, you can now drink beer.I think we can all agree this isn't porn, but I don't blame the dude for trying to get a piece of the action.