Well I don't mean by doing it without telling everyone. I mean wait until it dies down, then just be like oh btw 15.X includes CSAM scanning as a change log bulletin.
Given the uproar on this change, and the fact that the uproar was big enough to cause this delay, can you imagine the bad press if they come back later and roll this out quietly?
Editing to add: I think this will play out more like the butterfly keyboard debacle. They won’t ever really acknowledge how bad the original thing was, but they’ll return to a solution the community finds palatable (server side scanning), and wrap it up in a bow like they did with the “magic keyboard, now on our laptops”.