The incharge of the situation statement proves my point. Too many people are blaming the bus driver, the school administration, etc. The person in charge was the 16 year old, they know right from wrong. The next level for in charge is the parents, too many parents want kids but don't want to be parents in the tough situations, or they want to be the "cool" parents and friends to their kids. They are your kids, not your friends. You can act like friends when they are grown, but when they are growing they need parents that are in charge and showing and instilling in them a sense of right and wrong.
I actually empathize with your general statement. A teenager should be able to have the competency skills to own their actions.
Given the limited amount of information we know about the teenager. He rides a bus to an after school program with younger kids and can be aggressive to peers. I am following a safe assumption there is probably more to the story about this teenager that we will never know, nor do we have the right to know.
It’s not an easy situation, but it is also why people are paid and trained to manage those situations. Confronting the teenager or his parents, especially given what we know might feel good in the moment, but ultimately leads to bigger issues for yourself, or maybe even worse, your child.
Again, not easy and doesn’t necessarily feel right, but supporting the administration and making sure they get it right, aka community involvement and maybe a good lawyer end up being the best option.