The existence of a CSAM implies a crime was committed though, since there is no way to legally produce such an image. Possessing a CSAM image is pretty much the same as aiding/abetting the original crime.
A private deepfake image is not the same.
A private deepfake image is not the same.
Well if those images are illegal, you're right that there's no way to produce them legally, but that's because they are on their face illegal.
If you mean there is no way to produce CSAM that doesn't break other laws, I think you're wrong - e.g. see the case of teenagers taking nude pictures of themselves. That is an otherwise legal thing to do, but having those images is illegal, as I understand it, and you can search Google for many examples of teens prosecuted for sexting images of themselves. I don't know if anyone has been prosecuted for merely having nude images of themselves, but that might just be because no one would even know about it, necessarily.
There are plenty of incredibly disturbing videos and images of some of the most gruesome crimes committed and they are lawfully accessible and obtainable on the open Internet, including some such images on Wikipedia. The documenting of a crime is not and has never been illegal.
On a related note, I assume there is already a lot of deepfake CSAM in certain circles. If that is ruled legal, it will make finding and prosecuting real life CSAM creators much more difficult.
At least in the US.