Well, maybe this stuff can be called art or free speech. However, the US constitution only guarantees that the government can’t persecute you for your expression. It says nothing about corporations or private individuals.

Facebook is not the government. Facebook can and should do something about hateful material on its platform. People aren’t calling for the those posting AI child torture images to be arrested - they just want Facebook to stop spreading their material.

If you decide to use AI to create child torture porn, you should at least be forced to publish it yourself. Why should Facebook help you?