It happened last year, I think, and I seem to remember something like that as the driver's defence.
In fact, I don't understand why the courier grabbed on to the car, but that's by the by. It doesn't explain why the driver drove into him in the first place. It sounds to me like that was a deliberate move on the part of Bryant (why?), but maybe I'm reading too much into it. In which case the appropriate charge would not be “criminal negligence causing death and dangerous driving causing death” but either murder or whatever the technical term would be for "assault which was not intended to kill but was clearly going to lead to at least serious injuries and in fact did kill" (manslaughter?).
But petitioning Penguin not to publish the book? No, I think they should publish it. Let him explain what was going through his mind at the time and since. It's not often we get psychological insights into such moments, particularly connected with road deaths. How much we can trust it I don't know, but even a lie tells us something.