Remember: the hash collision is only the first step in the process. You also need to convince the Apple reviewers that the image is pornographic, and convince the NCMEC reviewers that the image is in fact the same as the one that it met a hash match with (apparently by magic, since you're imagining that the original image that you have to make a visually-indistinguishable match to isn't available).

I ask again: how is this process any more potent than any regular old fashioned pornography framing?