Huh?

I got a headache trying to parse your point (and I still don't see one).

> As a result, any security design that depends on "root processes cannot get kernel privileges" on Linux needs you to be aware of the exception "unless there is owner consent", as opposed to the iOS variant, where the exception is "unless Apple as kernel developer consents".

You are describing a distinction without a difference. With Apple, the entity with the keys (Apple) is the owner and escalation may happen with its consent. With Linux, the entity with the keys is the owner (maybe local admin, maybe not) and escalation may happen with its consent. Your point?