Didn't mean to imply you were suggesting to trust them and I agree, the claim is impressive.

But if I understand correctly, researchers can't research the closed off code, only what has been disclosed? So could there be hidden back doors?

Also, if we assume Apple's claims are true, Apple still owns users data doesn't it? And so users could have their accounts closed. Great punishment to hold over the heads of users, especially at the behest of a government. Users comply otherwise loose a lifetime of data? Moreover, as people become addicted to AI, the thought of living without it would become unbearable and so, induce compliance to whatever dictate of the day.

In the end, Corp remain in control of its users.

Moreover, you have to have a sense of shame before you can feel embarrassed. The majority of scientists and doctors have made some pretty outrageous claims in recent years, and majority of media outlets have not shamed any of them. And if it was all a lie, 99% of users wouldn't care anyway.