From most of the videos shown here when there are two dudes on a motorcycle they’re usually punk ass robbers. Love the video on DR where cars just turn and run over those robbers, shoot’em as they come up to the cars!
He’s an adult and responsible for his actions. Obviously he did something to the wrong person to bring this on himself.
And with those ears he should have heard him coming up behind him. No spacial awareness can be fatal.