I would imagine there was more than just one airline flying in and out of Honolulu, and United could have done their job better and put their passengers on one of those.
They could have, but they basically just gave us a list of airlines that flew to the mainland and told us they would honor the ticket. So we waitlisted. Continental finally got me a flight to LAX about 15 hours later but had the decency to tell me it would be at least 12, so I deposited my luggage with them and took a bus into town.