[dragonwriter]

> Image generation models capable of generating this type of content would necessarily need to be trained on the real thing

This is absolutely not true. Generalization is a key capability of image generation models.

> Certainly this opens the door to a whole plethora of new "it's AI art, I swear!" defenses.

The worst justification for a criminal prohibition that I can think of is that it is provides a convenient out for the difficulty of proving another, more clearly warranted, crime.

> After all, how can one definitely prove that CSAM is authentic or not, unless the chain of production is verified?

"Beyond a reasonable doubt" is not, and never had been, "definite".