These things are always initially introduced with good intentions and in a way that no-one can object. Then the scope expands. In this case I expect something along the lines of...
* Scanning cloud images for child abuse. No-one can object to that, right?
* Then extend it to scan for terrorism related issues. No-one can object to that, right?
* Extend functionaility to scan images at the phone level itself, because it prevents paedophiles and terrorists avoiding the tool by not uploading to the cloud. If you have nothing to hide, right?
* Extend it to scan for images for other crimes. It's only a small change. Some people might object but shame on them if they do.
* All images scanned for whatever is deemed public benefit. It's only a small extra step and you're already being scanned so why object?