We don’t know what kind of attempts the teacher/s made during the school year to get the boy to correct his behavior. Apparently, they were unsuccessful, or else this would never have been an issue in the first place. People tend to blame the teacher/s for everything (not that they aren’t for some things) but the child/ren and the parents are all integral for a successful education. The teachers bear responsibility here, but SO DOES THE KID AND HIS PARENTS. Like someone else wrote, the parents aren’t doing their kid any favors by teaching him how to be a ‘victim’.
IF she did, then what good did this 'parting shot' do for the kid? Nothing. It was immature behavior designed only to hurt the child.
The teachers bear responsibility here, but SO DOES THE KID AND HIS PARENTS.
I don't disagree with that, but the sole reason this child's behavior is being discussed at all is because the teachers couldn't resist acting like misbehaving children themselves.