You make a good point, but if my parents had caught a 12 year old me mouthing off to any adult under any circumstances I wouldn’t have sat down for a month. (And for the record, I’m pretty thankful that they never had a clue as to half the stuff that went on on my school bus.)(Or at least, I don’t think they had a clue, as I get older and rethink it, I realize they knew a lot more than I thought they did at the time.)
At least as described, I didn't see any indication that the kid was "mouthing off" to the driver. According the the story, she initiated the harassment, and the child's response was that Obama was pro-abortion.
Was there more than that? Probably. But again, the driver was supposed to be the adult in this encounter.