They boys should receive the compensation that anyone else might have received for being bumped even if the boys did not ask.
I think if your lawyer sends the airline a letter asking for a pair of 400 dollar vouchers, the airline will oblige quickly.
Apparently airlines nowadays use a large room for stranded minors because they want to be able to monitor the minors and it is undesirable for just one child and an airline employee to be together in private. But the airline would be responsible for quelling any disturbance.
Travel tips:
http://members.aol.com/ajaynejr/travel.htm