I think they're arguing that encryption done by someone else on your behalf is not actually in your control. And if the people who do control it are beholden to

I think they're arguing that encryption done by someone else on your behalf is not actually in your control. And if the people who do control it are beholden to the government requests, then they are not a safe option either. I'm not deeply familiar with Apple's encryption systems, but from the other commenters here, it appears that Apple holds the keys and also controls the source code and distribution to the device. It sounds like it might be trivial for them to invalidate their own security.