It's a matter of simple biology.
If you consider the width of the human oesophagus and the ease with which it can be blocked, then the notion of a man choking someone in this fashion doesn't need to get into a boasting contest - probably most men could do this if the circumstances are in place.
And that is the crux of the issue - if you forcibly block an oesophagus and shut off the air passage, the person will eventually die from lack of oxygen.
But since the human reflex to survive means that no-one is going to voluntarily allow this to happen, the implication is that force was used.
So the accused demonstrating the size of his penis is clearly not the issue here - and the notion that his partner simply desired his pleasure to such an extent that she was willing to die for it, is really not something the jury can seriously entertain.
Far more relevant in this case is going to be the autopsy result, and without wishing to pre-judge an on going case, I think it likely that evidence of force will be found, and presented to the jury in evidence.
We shall see.