I honestly don't know how you could mentally wiggle yourself into thinking that 8:45 seconds of someone being on your neck could have an alternative cause of death. Hell, but let's say it was something else. Let's say it was actually a heart attack that ultimately did him in. Does that matter? Surely, we can point towards the stress of having someone on your neck for almost 10min as a contributor...?
Honestly, I'm baffled by the mental gymnastics.
I think the egregiousness comes not from the move itself, but the duration a excessive use given the person was already subdued, in hand cuffs, on the ground, and not resisting.
I don't think anyone would complain about a knee on the neck of someone actively resisting arrest while they were getting the situation under control.