"open water" is the first certification level. If they did a class, pool time, and a set of "open water" (lake, quarry, ocean, etc) dives, they are certified divers and would qualify for the Epcot Divequest dives. Have your husband pull out the cards and see what they say.
And FYI, my husband has more than 200 dives and still ranks his dives at Epcot as some of his favorites. You would have fun watching them too.
PHXscuba