I don't read it that way. More like, "keep this extreme example in mind, and see if you still expect the guarantees to hold up".

If you don't, then they won't either for whatever activities you're doing, that aren't as reprehensible as CSAM, but some government may think otherwise.

It's kind of depressing reasoning maybe. But if a privacy-preserving system is actually that, then even the most technically-savvy terrorists and child abusers should have no qualms about using it as well.

on the wall at your dry cleaner is a sign, "we are not responsible if your clothing gets ruined" and there's a sign at the parking garage, "we are not responsible if your car gets damaged".

But, you have the right to expect that the dry cleaner and parking garage will take reasonable care with your belongings and will not act in ways that are negligent, the signs they put up notwithstanding.

There's no scapegoating, it's a question of what should a reasonable person expect from a transaction. Protonmail said they don't keep logs by default and that they also need to respect court orders.