You are totally wrong. If you get into some trouble on the bike, you don't die. If you get into some trouble on the swim, you die. You think little crashes on the bike because tryathletes don't know how to ride a bike is "exponentially" more dangerous than dieing on the swim? Unreal.
That guy didn't need to die on the swim leg. He may have gotten tired and tried to signal for help but he couldn't because he was surrounded by other swimmers drafting. What likely happened is that he got a bit tired and just started treading water to try to rest, bobbing up and down near the surface. But since he was drafting with the other swimmers, everybody just swam over top of him forcing him under water and causing him to drown. The drafting was the cause of his death.
And bike handling is an essential part of cycling. If you are dumb enough to closely draft tryathletes that can't ride a straight line, then maybe you deserve to crash a few times before you learn. Good cyclists will increase the space between them and wobbly tryathletes and draft towards the outside so they have an escape route should somebody go down. And good cyclists will tell at wobbly tryathletes to get to the back of the group if they ride like that.