As long as there is enough oxygen in the air, what's disturbing about it? People breathe helium/nitrogen/oxygen mixtures all the time.
I meant that it's disturbing that the amount of He needed to disable the iPhone is low enough that the standard sensors around He (which measure 02 levels) don't regard it as a major leak for He to be at that level.
Presumably, the sensors exist to protect humans, not electronics.
The devices are tested for usual STP. Nothing else, unless specified. They are done so not for human comfort, but for tested conditions. No more.
If you want extreme conditions, pay through the nose.
Yes, I'm allowed to be disturbed by that; why wouldn't you be?