It might not have been a passenger. It might have been an entertainer. They fly them in at various ports to do the shows. Maybe his plane was late and they didn't want to leave without him because they had nothing else. The ship has to move out of the harbor so they are not charged additional docking fees and they waited for him there.
I doubt very much the captain would go through that for one passenger unless it was a very important passenger.
Carnival Cruise Lines:
Fantasy 90, Celebration 95, Victory 05, Conquest 05, Spirit 6/06, Freedom 6/08, Holiday 7/08, Victory 6/09, Valor 9/09, Dream 6/10, Splendor 8/10,Conquest 8/11,Magic 11/11,Triumph 4/12,Spirit 7/12,Freedom 11/12, Triumph 2/13 - The fire cruise, Magic 1/14
NCL Dream October 2006, RCCL Mariner OTS June 2007, Celebrity Silhouette 2013