I already know the answer, but why are what I presume are gate agents employed by a private corporation allowed to detain a citizen who is not a physical threat to anyone over a contract dispute?
Refund his ticket and don't let him on the plane if you're that concerned, or otherwise handle it in civil court after the fact. Using physical force to detain him over a contract dispute should be illegal.
I get where you're coming from as the article is told from a specific perspective, but they were perfectly happy to maroon the kid in a strange city by making him do the full flight, so I don't think they were looking out for him.
I don't remember the specific age for domestic flights, but if he was travelling on his own without needing what is essentially a chaperone, then he was at least 15 or so. So a minor, but old enough to take care of himself. I don't think they had a duty of care any more than a McDonalds cashier does when a group of teenagers go there on their own to order food. I've done those kinds of flights when I was younger and its actually not trivial to just leave at the wrong airport when you get that kind of chaperone treatment.
These were security agents who pulled him out of line unprompted and took him into a secure room. Even if he admitted he wanted to skip-lag, that's not illegal so why bring him to a back room if not to intimidate him and get his parents to pay up?
I mean. You could read the article. It said that they took him to an interrogation room. And that his dad bought the ticket without knowledge that this was a frowned upon practice because they had been doing it for years.