I'd have to know more history on this before I'd condemn the woman too thoroughly. The teenage boy admitted to police that he had "threatened and cursed" the woman before. I'd like to know how often and exactly what he'd say and what his posturing was when doing so.
I'd also like to know what measures the school had ever taken to make sure this woman would be safe on the bus with this boy. I mean, if you've been in fear for your own safety for who knows how long and the boy who's been threatening you tosses a younger boy over a seat who then hits you...well, I can be a little more understanding of snapping.
From what the article was showing, this wasn't some squeaky clean kid who was just being a regular boy and then got whomped on for it. It sounds like he was a bully with a history of threatening the woman and who obviously had no problem flouting rules [I mean, come on, he was rough-housing enough to actually toss a boy OVER a seat?].
No, her behavior wasn't right, but I'd really like more of an accurate history of what led to that moment before I condemn her too harshly. He may well have had a bit of a well-deserved smackdown coming from someone. Or, she may be just a short-fused whack-job. I need more info to know what I think about the situation.
Edited to add: I found this article that gives more details about the incident. Apparently, the boy has been threatening physical violence to the older woman regularly.
http://www.theledger.com/article/20111011/NEWS/111019874