I'm not a fan of his constant sales pitches, but I do like some of his ideas.

Which ideas of his are wrong?

As far as ketosis goes, it sounds like he promotes exogenous ketone sources (he sells Brain Octane and XCT oil), in addition to having glucose as a source of fuel. I found a product that has the C8 and C10 MCT's on Amazon for much cheaper and works well.

Amazon.com: Premium Coconut MCT Oil, Huge 32 Oz. Easier To Absorb and Digest. Triple Filtered. Independent Quality Testing for every batch. Made in USA.: Health & Personal Care

The brain needs glucose for sure, but the damaged brain (from my research) doesn't process glucose well, at least not immediately post-trauma. It comes down to each individual, but it sounds like the brain "prefers" ketones.

Additionally, I've read that the metabolism of the injured brain doubles post-injury. If the brain isn't getting fuel, neurons die.

Humans haven't had a constant source of food until the last few hundred-thousand years. We're adapted to burn fat. Even if a ketogenic diet doesn't work for some people, more research and anecdotal evidence is pointing towards the importance of good fats in a diet.