Here's another question asking about Russell. While I'll admit, I haven't read his book or heard him on any Podcasts, it doesn't sound like he's taken too seriously; I'd read him with a safe dose of salt on hand. Here's what I found to be one of the better reviews of his book on Goodreads.

Sounds like he's a bit of a 'pop culture history' writer who prefers to go along the revisionist route: reimagining/reinterpreting how we understand historical events. While this does have value at times, there's no use in being a contrarian just to be a contrarian, which sounds like what Russell does. Like any other discipline, historians should let the facts lead us to our conclusions, not walk in with a predetermined conclusion and pick out the facts we like to fit it like we're at a buffet.

In the linked thread above, the poster who answered, /u/sillybonobo, also links to this article written by Russell and I think his conclusion is spot-on: Russell sounds a lot like someone with an axe to grind. It doesn't help that he explains away his own argument's shortcomings or weaknesses away by blaming them not on intellectual weaknesses, but on dislike from others:

During my talk, a Columbia professor who had been named by a national magazine as the most important public intellectual in the United States, stared at me with what I took — rightly, it turned out — to be disgust. Another walked out before I finished. One of my graduate school advisors asked a series of hostile questions. Other colleagues told me after the talk that I was “courageous,” that I was “wonderfully, relentlessly revisionist,” and that I made some famous historians “look like dinosaurs.”

But emails came into the hiring committee from “important places,” I was told, calling my ideas “improper,” “frightening,” and “dangerous.” They said my ideas had no place in the academy and insisted that I be terminated.