[dredmorbius]

Ballistic protection (and much more rigorous materials and component testing) seem like they'd have played a more critical role than a seatbelt in this particular instance.

That's not to say that personal restraint system isn't a critical component of safety equipment. Just that its role in this specific mortality mode would be negligible.

Helicoptors are complex. There are many ways they can kill you (or those around you).

[tyingq]

In this particular case, his neck wouldn't have been hit/cut if it had stayed inside the plane of the open frame door.

Anything could have happened. But for what did happen, a 4 point belt would have sufficed.