Eh, while I'm happy(ish) for her, even when making it more simple, she actually doesn't quite know what she's talking about. Or she is hiding the details to serve a political point. Both are possible.
Full Disclosure: I'm something of a pure expert in this area by necessity. Which means I *do* know how those systems work and *why* they worked in her case.
The first note is that she's really lucky the MS wasn't hiding a lysosomal storage disease or some other dysfunction with lipid processing. While she does "eat better", that's got very little to do with what actually worked. She seems to have gone 0 grains, and very low carbs. What she actually did was throw her body into ketosis and changed the entire energy pattern to actually work around the mitochondria as much as possible. She mostly shifted the nervous system to Ketone utilization via the Liver's breakdown of fats to Ketones. She was actually starving the mitochondria out, until the Ketone level was sufficient.
It's a wildly effective treatment for a number of rare nervous system disorders, but extrapolating out from the tight requirements of a degenerative disease's diet to the entire population is pretty foolish. Does it mean the SAD is good? (Standard American Diet) No, but her personal story has zero to do with it.
And that's before laying into her over the Noble Savage fallacy, history, food quality, food supply and expandability. But what he's really making is mostly the same mistake that modern Medicine makes: it is good at issues it understands, but is pretty much just guessing at unknowns. She found something that worked for herself and thinks "that's the key!", but she doesn't seem to actually understand the systems.