Look at it this way, the defense can argue that the shoddy driving was not the direct cause of the injury. They could have been rear-ended by a space ship with an unlicensed drunk behind the wheel... or stick... whatever. In which case John could still be in a coma since he didn't bother to put on a belt. They have to prove that the lack of seat belt was the direct cause of the injuries. Now if the plantiffs argue that the seat belt wouldn't have prevented the injuries, they'll run the risk of validating the defense's argument. It may be wiser to ignore the defense's stance and focus heavily on the driving as the direct cause and hope the defense can't put up a strong seat belt case.
Was the driver wearing a seatbelt? Yes? Then the plaintiff gets screwed, cuz the driver made it out no probs, in the same accident. No? Then the defendant pays teh moola, i bet.
Anyway I'm sure there are a lot of cases similar to this one, but this one gets media attention cuz of the 'Hogan' name.
+1 to not giving a fcuk.