> But its the law and he knew full well that there was always a risk that he would be bumped from a flight, as any passenger does.

The contract with United says you can be denied boarding, but not much about boarding and then being kicked off after.

> If he did not want to be bumped he should buy a business class seat.

That's no guarantee. http://thehill.com/policy/transportation/aviation/328495-uni...

> Geoff Fearns, who purchased a full-priced first-class ticket to travel from Hawaii to California, was asked to get off the plane by an airline employee because the flight had been overbooked, according to The Los Angeles Times. “That’s when they told me they needed the seat for somebody more important who came at the last minute,” Fearns told the newspaper. “They said they have a priority list and this other person was higher on the list than me.”