If they are using this to introduce something closer to end-to-end encryption then it seems like a clear win for users. Today photos are not end-to-end encrypt

If they are using this to introduce something closer to end-to-end encryption then it seems like a clear win for users. Today photos are not end-to-end encrypted, there is nothing preventing Apple from decrypting your photos if they want (or if they are asked by law enforcement). If a part of this implementation is to make it so only the user keys OR the CSAM keys in the case of a match are able to decrypt the photos then that is a clear step in the right direction over the current system. It's not real end-to-end encryption, but it still prevents Apple from just decrypting your photos without probable cause of a very specific crime. If that is the case they should have made it a lot clearer in the initial announcement though.