To clarify, I am aware you are objectively describing the legal situation. I am not making a legal, but an ethical argument. We seem to be agreeing.

There is even a Wikipedia article about the legality. It's quite complicated in a lot of places because people really like to ban it but it very much is free speech or protected artistic expression in countries that have these concepts: https://en.wikipedia.org/wiki/Legal_status_of_fictional_porn...

To be clear fictional pornography about real children has to be distinguished from fictional characters. Even when the depiction is purely fictional. Sexualizing real children is unacceptable.