I am glad to hear that he has made the decision to get a certification before traveling. Many folks make the mistake of taking resort courses.
Obviously getting some experience is better than none. As I said, unfortunately most of the cruise ship destinations are not really the best dive locations due to the poor reef conditions. Even if there is decent diving in the locale, cruise ship passengers will almost never get there as the dive operators actually triage cruisers differently. After having the good fortune of diving many of the pristine reefs and oceans of the world, most of the locations which a cruise ship diver will see would make me cry. The coral is broken up, bleeched or dead - the marine life sparce - many people see a few pretty fish and think that's what diving is all about.
If your husband wants to experience good diving, he will have to look elsewhere in a different venue. In many respects, froom a selfish standpoint I am grateful that few people really take up diving - I would hate to see the cruise ship mobs all over my reefs. On the other hand, those who (Pay And Dive Instantly) and hang out with 80 people on a barren reef come to think that there is really nothing out there anyway - whats wrong with building another cruise ship terminal.