We had a lung overexpansion injury on our Red Sea trip, which luckily ended much better than this one. But it wasn't from panic or bolting -- as far as we could ever puzzle out, it seemed possible that the diver got a bit disoriented inside of a wreck which lay at a bizarre angle, and was unaware he was ascending for a bit. What it taught me is how little pressure change is required to do damage.
If this experienced diver began a routine ascent from 40 fsw with 800 psi and only ten feet later, felt distressed enough to demand a regulator from his daughter, it sounds as though something was terribly wrong at that point. Either a health problem, or he just held his breath at the wrong moment while going up.
Tragic story -- I hate to hear these where someone's child is the buddy and has to try to help his or her parent. I don't think you would ever quite get over that.