American Affairs Journal was actually founded by a conservative nationalist as a pro-Trump journal, designed to "to give the Trump movement some intellectual heft." The editor changed his mind (and his political position) 6 months after the election, after Charlottesville.

I think that what you see here may be some amount of bitterness after watching how events play out and what actually changes. The working class he decries as powerless were his people (he grew up in a small town in South Dakota); it's just that now that we've had 3 years of Trump he sees just how ineffective it's been.

The author explicitly acknowledged that the deplorable majority can pull the lever once every four years, “At most, working-class voters can cast their ballots for an “un­acceptable” candidate, but they can exercise no influence on policy formation or agency personnel, much less on governance areas that have been transferred to technocratic bodies”

But once in office their guy maintains the status quo even though populist rhetoric got him into office.

So far this theory appears to be true. Historical data corroborates. What is less certain imho is that grassroots activism has ceased to be ineffective. Nobody expects the pitchforks and guillotines until they show up on their doorstep.

Which variables?

I agree with you, the author seems to assume that Brexit/Trump/France are all one-off political movements.

I'm not even so sure as to how homogeneous tech i if the drama at Google is any indication. Academia probably is as they have a financial interest in the federal government expanding.