Oooooh nasty. As someone who also does triathlons, and rides a TT bike - yes it does take that extra movement to get to the brakes and I am wary when riding in built up areas and don't go onto the bars much if at all - but equally if you want to train on such a bike you have to train on the bars and there's always the balance between making progress and being wary. It might be that even if he'd been on a road bike on the drops he wouldn't have been able to stop in time.
I apologise if this appears to be inappropriate speculation - I intend it to be more a personal reaction. Best wishes to your colleague.