Yup - that oversized animal needed to be put down like the beast he is
From the way he was talking before the altercation, the attacker seemed crazy.
Too bad for the bus driver that he didn't pick up on that.
He should have been a little more careful considering how empty the bus was (not many folks to provide potential help in case things turned violent). Seems like he should have called the cops though it could be that he's under a lot of pressure to maintain his schedule to the point where calling (and waiting) for police help would have caused him some heat from his bosses.
In hindsight, though recovering from black eyes and a broken nose at his age likely really sucks, the bus driver is lucky that crazy dude did not have (or at least use) a weapon.