Nice idea but a cruise ship isn't really capable of providing the relief needed. Years ago in a similar situation the US sent an Aircraft Carrier to the Philippines. A carrier is much more capable of providing relief than a cruise ship. It has food for thousands of people for an extended period of time, water desalinization of hundreds of thousands of gallons of per day, hospital facilities equal to a major medical center, and a fleet of helicopters capable of transporting aid to where it's needed.
U.S. sends aircraft carrier to bolster Philippines relief efforts