We are talking about a cop dealing with a guy who is in a vegetables state and continue nto compress him.If the manner of the restraint wasn't known to impede breathing then yes, absolutely, it is helpful to the defence.
It would mean he had a breathing impediment not related to the restraint. If that unrelated impediment could be the cause of his death, then of course that's helpful to the defence.
Let's not forget the context here. We're not talking about medical professionals tending to a patient in a hospital setting.
We're talking about cops dealing with a guy who is actively resisting arrest, and who has a previous criminal record, and is high on who knows what..
I believe that is why the jury voted how they did, plus some key statements from experts showing classic gf body movements to a trained eye of how the human body was fighting for air.