The content isn't banned from the phone, just iCloud.
A list of banned content already exists on Facebook servers, and we have no way of auditing if that list only includes CP. Where's all the outrage over that?
Because Apple is one boolean flag away from total on-device surveillance of your phone. In the past they've pushed back on this kind of thing because they said they'd have to build new capabilities into iOS to allow it. Now it's just a matter of policy and Apple has a track record of bending policies to suit various jurisdictions.
If you actually read the white paper on Apple's CSAM system, you'd know it is far more than just a boolean flag away. The system was specifically designed to prevent the kind of abuse everyone is worried about. I've been looking into the system deeply, and I fail to see how it could be co-opted for nefarious purposes without a complete redesign. Even in the most optimal attacks setup by a security researcher, I can't see how it gets anywhere near the worst-case scenario.
The worry seems to boil down to; "they could CHANGE it in the future". If the concern is about the potential for a future system, then such concerns are infinite, since infinite new systems could always be proposed or deployed. I would rather conserve my outrage for that moment, rather than be the boy who cried wolf.
Though this certainly isn't an argument for apathy. I think the amount of push-back Apple is getting is probably healthy, even if it's hyperbolic.
A list of banned content that lives on your phone sets a new and alarming precedent.