not at all. I'm pretty sure nobody here thinks CSAM should be legal. The topic at hand is whether that means everyone should be subjected to blanket surveillance by default.
Just because there's child abuse out there doesn't mean you can walk into a random persons house and rummage through their drawers, and by the same logic Apple or anyone else should have no business digging through my phone.
It's not idealistic at all, it's simply opposition to surveillance of people who have done nothing to warrant such suspicion. I don't know about the US, but here in Germany we have the so called Briefgeheimnis. (literally: secrecy of letters). Privacy of correspondence is almost sacrosanct and can only ever be violated under extreme circumstances, not casually or systematically, that's what the Stasi used to do.