The same thing could have been said years ago about solar power in california.
But with PG&E's regulatory capture and people paying 50c/kwh for electricity, solar is economically practical. Even with batteries! (and wholesale electricity is still 3-4c/kwh)
My point is that the math could change in a moment due to regulation and/or energy repricing.
(example: disallow non-electric planes at certain airports or certain distances; allow in-city electric flight; wholesale electric rate for electric aviation/shipping; etc)
(that said, writer is probably right about this moment in time)
The math would already change quite a bit if airplanes had to play on a level playing field. For example, in the EU there are no taxes on aviation fuel. For a country like Germany that's the equivalent of a yearly 7 billion euro subsidy.
Add fuel taxes and CO2 surcharges, and same-continent rail travel suddenly becomes a lot more attractive!