The article I read said he's going to get paid because the law states once you get voluntarily bumped the airline has to present you a written copy of your rights outlining timing of rescheduling, repayment/credit guidelines, & reimbursement for additional expenses. They didn't do that before calling security.
I've been on a flight with the same situation and they held up that paper, read it on the intercom, and said "we're staying here until someone gets off".