The guy was just unlucky. What are the odds a chock is going to fly forward into the cokpit and jam the controls. I agree with the guy who says every pilot has hot dogged and if he says he hasn't he's lying.
I know that a lot of hot-dogging goes on out there. As far as the guy just being unlucky...perhaps, but sometimes you make your own luck. The odds that something weird (like the chock flying into the controls) dramatically increase when operating an aircraft in an unsafe manner. Truly an avoidable tragedy.