I guess I don't understand the point. I would expect a 22lr delivered to the head to be a one shot stop. We also all know it was more than likely a lucky shot aimed for the COM that went way high. A 25yd head shot at night is not impossible, but not likely either. No one would attempt such a shot on purpose & I am sure that is what he told the shooting review board.
"Given adequate penetration, a larger diameter bullet will have an edge in wounding effectiveness. It will damage a blood vessel the smaller projectile barely misses. The larger permanent cavity may lead to faster blood loss. Although such an edge clearly exists, its significance cannot be quantified".