the AI has to be trained on something first. It has to somehow know what a naked minor looks like. And to do that, well... You need to feed it CSAM.

First of all, not every image of a naked child is CSAM. This is actually been kind of a problem with automated CSAM detection systems triggering false positives on non-sexual images, and getting innocent people into trouble.

But also, AI systems can blend multiple elements together. They don't need CSAM training material to create CSAM, just the individual elements crafted into a prompt sufficient to create the image while avoiding any safeguards.