Earlier quoted context omitted.
Client side scanning of inappropriate pictures is of content you'd ordinarily be sending them as anyways as well. The proposal was only to do this if cloud services were/are enabled.
A significant number of concerns aren't about the feature as proposed by Apple, but the slippery slope it creates.
And personally, I know this won't affect me. I don't own such content. I don't use the cloud without encryption first (thanks Cryptomator). However I just hate the feeling of my own phone constantly looking over my shoulder on someone else's behalf. Is that so weird?