For other people who only read the comments and don't read source material:
"Turn on communication safety to help protect your child from viewing or sharing photos that contain nudity in the Messages app. If Messages detects that a child receives or is attempting to send this type of photo, Messages blurs the photo before it’s viewed on your child’s device and provides guidance and age-appropriate resources to help them make a safe choice, including contacting someone they trust if they choose.
Messages uses on-device machine learning to analyze image attachments and determine if a photo appears to contain nudity. The feature is designed so that Apple doesn’t get access to the photos."
Privacy erosion is gradual, that's why they keep getting away with it (well, that and "think of the children!").
It’s an opt in feature, that’s part of the parental controls settings, and it does all processing on device. Apple is not Google or Facebook, and has demonstrated that it has no desire to access your images or data.
Your slippery slope argument is so pointlessly stupid it’s equivalent to arguing that the addition of speed limits is a slippery slope towards not being allowed to drive. Eg meaningless to the point where it erodes the meaning of the term in contexts where it actually matters.
LGTM