If they used H2 (vs He) for buoyancy they could make (liquefied) H2 fuel very cost efficient: When you want to come down you are high up and it is cold! Perfect time to liquefy!
Making H2 gas is also subsidized on the production end, as Airship travel is cheaper than any other method, so making H2 has that cost advantage.
Safety is not an issue for transport. Human travel has that tradeoff though over He.
It's less of an issue. You still don't want a burning hydrogen zeppelin crashing down on a populated area, and unless you've fully automated it you'll still have human crew aboard (though they'll be better trained and equipped to deal with problems).
If it's filled with Hydrogen, it doesn't burn for very long - it would be an explosive burn. The cargo is still aloft in the air though, but that's also a theoretical problem with planes.
Making H2 gas is also subsidized on the production end, as Airship travel is cheaper than any other method, so making H2 has that cost advantage.
Safety is not an issue for transport. Human travel has that tradeoff though over He.