[user104658]

Here's another thought to muddy the waters;

I don't imagine for a second that people would be coming down so heavily in the driver's favour if this was a girl mouthing off, and he called her "fat bitch", threatened to "punch her face in" and physically shoved her off the bus.

Give that some thought, and think about why that wouldn't be OK. Now think about why it's apparently OK to do it to a teenage boy.