It's just another principal-agent problem, and I agree that a fully self-sovereign life, with no dependence on trust or agents, is an unrealizable ideal; and, that a decent solution (while not perfect) is reputation stake and aligned incentives, check and check in Apple's case. I too think Cook is sincere, and I trust them as far as I can throw their products, which is to say, a little. (The Apple Tax is so they don't have to rely on a sketchy big-data business model.)
That said, computing and InfoSec have some unique contours, in a way that trusting a mechanic or a lawyer does not. Those can have catastrophic failure modes as well (crashing from a shoddy repair, getting sued based on bad legal advice), but they aren't systemic to society, and have lower switching costs.
And I ultimately think it's a false choice. When it comes to meatspace security, it's possible to have trusted and accountable public institutions, and allow citizens to have some means for self-sovereignty (2A, locked doors). It would be foolish to rely only on one or the other, either as a society or an individual.
So I'm deeply grateful for the Stallman types, pushing forward the capacity for self-sovereignty. Even if it doesn't currently meet my needs from a risk/benefit tradeoff, I still benefit from the ecosystem, and its BATNA, and I look forward to the day I sever my dependence on Apple's ecosystem, whether or not they betray my trust.