In return the airline could have sweeten the deal by giving the new volunteer a free flight by refunding the cost of the ticket and maybe adding some coupons that don't expire. Or even giving a $200 inconvenience check would have been cheaper.
Actually I think the offer they gave him was 2 times his ticket price.
That is a big part of choosing who is voluntold is how much their ticket cost because DOT requires you to reimburse them double their ticket price.