I've got to say, I really am wondering why this man's defence team never even raised the possibility of instantaneous death from carotid sinus stimulation.
Because if a) they had done so, and b) it really existed, then this would have been a rather useful defence for the man - after all, if they could claim that Millane consented to being choked in an erotic-asphyxiation sex game, at which point the man got Millane into a choke hold of some sort, at which point Millane died more-or-less instantaneously, at which point the man panicked etc etc. It's not a perfect defence, but without doubt it would have been a far, far better defence than the one he actually offered.
So we truly are left with only two possibilities here:
1) Instantaneous death from carotid sinus stimulation is a medically provable phenomenon which is common enough to have been at least a reasonable likelihood in this case..... but this man's lawyers somehow failed badly in their duty to offer this up as a defence;
or
2) There's actually no scientific evidence supporting the notion of instantaneous death from carotid sinus stimulation..... which is precisely why this man's lawyers did not propose it in his defence.
I wonder which of these two options might be the correct one.