In the end, there are some pretty large questions:

1. How much did this cost (presumably) the airline?
2. Who pays?
3. Are the culprits (mother & son) on a no-fly list now?

If the answer to # 2 is us through elevated ticket prices then it's a problem. It either takes a village to raise a child and pay for their mistakes therefore societal norms are individually enforceable, or, it is exclusively the parents responsibility to raise the child and pay for the mistakes. It must be one or the other, there is no in-between.