> how competent apple's code review practices are.

Thousands of developers over a decade have touched code going into iOS & Mac OS and so far have a pretty good track record on internal espionage and back doors.

> remember that time you could bypass the root password

Pretty dumb mistake, but willing to put money on them that it won't happen again. I think you severely underestimate just how competent Apple (and Google, Facebook, or Microsoft) are at their job given the enormous complexity of the problems they solve.