Very sad to hear, best wishes to his family for their bereavement.
It'd be worth while people checking their seats, mounts, belts and components in the car like roll cages, make sure there is sufficient padding. Make sure this is NOT overlooked in your MOT test.
I know Starlet seats are prone to rocking forward a little, this happened to my passenger side. Could this potentially harm someone?
Obviously we don't exactly know what happened but goes to prove that even an inccident with the shell shape intact can be a potential fatality.
We're only as strong as our weakest point, be careful and safe people!