For many people this is a reasonable risk. If they pulled something like that it would start a huge legal battle, and it would seriously harm their reputation.

For many people this is a reasonable risk. If they pulled something like that it would start a huge legal battle, and it would seriously harm their reputation. I suspect that pushing out a change of this sort would also require a system update, which you could always delay until it's been carefully vetted by others. At least with Apple you can maintain a fairly small chain of trust, since they have greater control over their hardware. Being in control of the encryption keys is unlikely to protect you from hardware backdoors or state-sponsored attacks.