A head injury that results from speed or post-strike collisions is still recorded as a "cyclist head injury" so I don't think your points change the numbers.
Please note, I'm not trying to argue against helmets. The point is that arguments over helmets deflect the conversation away from the people sailing around recklessly in two ton metal boxes. Every time there’s a collision involving a cyclist, the question is "was he wearing a helmet?", not, "was the driver paying attention?"
The safest places to bicycle are in the nations where there's the lowest rates of cyclists wearing helmets. This is a car problem, not a bicycle problem.