This is what happens when you let the village raise your kids instead of yourself.
If it were my boy, I'd be spending an hour profusely apologizing to that lady for my child's horrible disrespect, and then beat his ass until he could not sit for a week. He wouldn't have to wait for the school to kick him off the bus for his bad behavior, either: I'd yank him off personally and have him walk to school for the rest of the school year, at least, no matter the distance ("takes you 2 hours to walk to school? Well, then I guess you aren't sleeping in until 10 minutes before the bus comes anymore, are you?) I've got a deep store of parenting wisdom bestowed upon me by Senior Chief Petty Officer Dad to dip into if it were needed (I really was a little shit as a kid, and so dad had to get more "creative" with me than he did with others), and draw up measures and tactics that the child can barely comprehend exists.