The only way to prevent the disaster would have been if the pilot had chosen to land in better conditions elsewhere, which was very feasible, considering he had had enough fuel remaining to reach all the way to California. Hydrogen is less flammable than gasoline. The self-ignition temperature of hydrogen is 550 degrees Celsius. Gasoline varies from 228-501 degrees Celsius, depending on the grade. When the Hindenburg burned, it took some time before the hydrogen bags were ignited.
Hydrogen disperses quickly.
So when a leak occurs, the hydrogen gas quickly becomes so sparse that it cannot burn. Even when ignited, hydrogen burns upward, and is quickly consumed, as shown in the Hindenburg picture. By contrast, materials such as gasoline and diesel vapors, as well as natural gas are heavier than air, and will not disperse, remaining a flammable threat for much longer. Hydrogen is non-toxic. By comparison, all petroleum fuels are asphyxiants, and are poisonous to humans.