I live in (moved to) Europe, and the railways are far more developed than in the US. But as far as I know, they all have to be heavily subsidized by the governments to even function. None of them operate with a true profit. Here in Germany, 2.2% of the latest federal budget is to support the railways. This is despite the railways being privatized (into a government owned corporation).
And while trucking is also subsidized to an extent, and it's a difficult business, but people do successfully operate trucking companies.
Airships might have the same problems as rail does with intermodal connections, but it's worth a try to see how the profitability equation works out (in real life, not MBA-land).
_Maybe_ it's feasible for large multinationals to run direct routes between their warehouses, with trucks being used for last-mile delivery. The only cost is operation; in comparison with rail where the infrastructure is a constant sink, and in comparison with trucks where the infrastructure cost is outsourced to society.
Trucks pay most of infrastructure costs through fuel taxes and registration fees.
I could feasibly reach all cities and _most_ large towns by rail in Germany. Sure, it's slow as heck if you're not taking the express train with no transfers and few stops. But the infrastructure is there. Whereas in the US there are massive areas where the nearest train connection is hours away.
I assume there are factors with freight trains I don't know anything about, and if they're as profitable as you say then the infrastructure is actually very optimized for profitability; if there's somewhere worth reaching, the trains reach it.
I feel like this is a bit naive. The true competitor to trucking is rail. But trucking is preferred because it's point-to-point and you don't have to deal with intermodal connections. Airships would have these exact same problems (unless you invented some way to build routes and drop off containers at specific addresses - but then you are back to it being slow again!).
So the only real market would be replacing container ships with something slightly more expensive but faster. But even using his own math - a fleet of 25,000 airships each with only a 500 ton capacity, and each being twice as big as the biggest airplane ever built - seems like a nightmare. All to only capture half of the global shipping market!