Massive airships flying 90/km an hours are LESS susceptible to blockades than cargo ships? I think I'll need a little more explanation than that. Seems like a shoulder-mounted rocket launcher would be more than enough to bring one down.
If you think about it, it makes sense: they are massive, so the loss of pressure from a bullet hole isn't a real concern. And while the right hydrogen-oxygen mix is explosive, hydrogen needs oxygen to even burn. But there isn't any oxygen in the tank bladder. The escaping hydrogen can burn as it mixes with air if it finds an ignition source, but as long as your hull is from fire resistant material the flame can't do much, and is probably extinguished by the next wind gust.
Of course the "make your hull from fire resistant material" is where the Hindenburg went wrong. Her hull material could have been used at rocket fuel, the engineers just didn't realize that.
Don't even need to pop all the bubbles. Just enough for lift < weight. Gravity automates the rest.