"Smart Features" in the Messages app have always been explicitly processed only on-device. This is a big change if it is different than that.
I'm betting they'll make this opt-out, which is fucking shady as hell. And worse, I bet opting out your own messages doesn't stop someone else that is opted in from unknowingly/unintentionally transmitting all your messages that they received. Ugh.
It goes without saying that this absolutely will not pass constitutional muster.
You can categorically try to ban pornography but the second you try to ban it based on its content and not based on it being pornography you no longer have a leg to stand on.
I wish there were some way to have criminal consequences for deliberately passing unconstitutional laws. It definitely feels like it's some kind of sedition, violating your implicit or explicit oath of office so profoundly.