WOW. This is one of my nightmares, and I have another 11 years to think about it. Perhaps a form of Hades?
I am stunned that he wasn't wearing a seatbelt and still walked away. This must be some statement regarding the passive safety of modern cars and trucks. The truck gave its life to save your son's.
I know there used to be a clause with USAA insurance that if the driver wasn't wearing a seatbelt they may not cover damage/liability. Hope that isn't the case with your firm!