Regarding your second paragraph of the legality, Apple doesn't incriminate you even if they send the image off and a image reviewer deems something CSAM. If Apple does file a police report on this evidence or otherwise gives evidence to the police, the police will still have to prove that (A) the images do indeed depict sexually suggestive content involving a minor, and (B) you did not take an affirmative defense under 18 USC 2252A (d) [0], aka. they would have to prove that you had 3 or more actual illegal images and didn't take reasonable steps to destroy the images or immediately report them to law enforcement and given such law enforcement access to said photos.

The biggest issue with this is, of course, that Apple's accusation is most certainly going to be enough evidence to get a search warrant, meaning a search and seizure of all of your hard drives they can find.

0: https://www.law.cornell.edu/uscode/text/18/2252A#:~:text=(d)...