"a bit of a WTF to say the least."
Perhaps I can help clarify it a bit. Note that I liked the guy and his attitude (although I never met him) but have never embraced his research, may as well get biases out of the way.
As a psych prof he became very interested in WHY people get hungry. If you can control when and what you desire to eat, then you can eat whatever you desire whenever you want, yet you can trivially control your nutrition / weight.
Needless to say the hair shirt crowd and the neo puritan crowd see this as a direct attack against their core beliefs, no improvement should be possible, should be allowed, should even be non sin ful to think about, without agonizing suffering. Who is being rationally scientific and who is suffering from a mental illness impairing their day to day lifestyle is an interesting question where I have an intense bias.
Personally via experience I agree with most of his general theories although I disagree or have no opinion WRT some of his techniques and choices. For example I have a very low refined carb low grain low sugar diet, and the idea of eating a sickeningly sweet snickers bar now is kinda nauseous, so although I could trivially afford, obtain, and eat an entire box of snickers bars, there's no way I'd do it other than a survival situation, although as a young-ish adult I gobbled those things up with predictable results.
Seth's theories about how to get to that kind of ... mental state or whatever ... might sound a little weird. But they worked for him, and seem appropriate for a psych professor to professionally comment on, so he's probably completely correct, however weird it may sound. A psych prof commenting on psychological state (at least WRT appetite) probably has more wisdom than any CS/IT guy on HN commenting on a psych topic...
The controversy is all in the application. His theory seems sound, now its all people freaking out about how it can be (mis)applied. That's where all the screaming is happening, no one at a professional level seems to disparage his actual theoretical psych work.
Its like debating the morals and ethics of Maxwells equations in a debate about net neutrality. Maxwell's probably right; doesn't imply much one way or another about the morality of the position purchased for the FCC. Although both topics are certainly in the same field of human endeavor.