I've never actually believed that it was just the paint, nor just the hydrogen, that led to the disaster. It was a combination of things. They had nitrocellulouse as a padding material for the hydrogen cells, then they had powdered aluminum covering an iron oxide sheeting over those cells. The combination of the hydrogen gas, the thermite covering, and the guncotton insulation all led to the disaster. If it was just the hydrogen, then the disaster would not have been nearly as bad as there was no way that enough oxygen could fuel the fire. As soon as the cells burst, the hydrogen would easily escape and diffuse up into the atmosphere. It was the guncotton and thermite reaction going on which helped fuel the fire.