I still recommend Mr. Fart's Favorite Colors as a refutation, describing why all of these precautions cannot protect you in a real-world security model: https://medium.com/@blakeross/mr-fart-s-favorite-colors-3177...

  Unbreakable phones are coming. We’ll have to decide who controls the cockpit: The captain? Or the cabin?

Krstić: “Here’s how we reduce the chance that even Apple can access or alter X, and here’s how we can make that credible.”

Ross: “Even if you make X cryptographically airtight, the real fight becomes political/physical coercion: ‘ship this or else.’”

Those can both be true at the same time.