He missed a very critical point, and that its dangerous to fly to Xinjiang and Tibet due to high elevations. That's why they did high speed rail despite it 'not being profitable'. Its the only fast solution that is possible to use safely in bulk. China has actually had a surprising amount of politicians and top level business people die to this problem.

Nowadays they have somewhat alleviated the flight issue through Xinjiang by leveling out some banks of some rivers but this mostly only benefits flights from Central Asia to Xinjiang. Airlines are basically forced to only be near these rivers and valleys because flying over the mountains is so dangerous. In Tibet, they have done similar. If you look at flight paths from Tibet that have specially outfitted planes that go over very specific paths over rivers, where if the plane motor goes out they always have a river in sight to land in. But the nature of this is that you can't have it in bulk and can only be during good weather days.