He hates on it because it impacts the profits of the products he sells. That's it. Never trust someone who is motivated by profit to believe a particular narrative.
Try reading these nutritional studies and you will see how much bullshit is behind them. https://news.ycombinator.com/item?id=20029519
It still amazes me that people surrender to nutritional authorities, instead of self-experimenting (cf. Asra Conlu on YouTube) and finding out the facts for themselves.
Unless you have read those studies, before seeing how much bullshit is behind them, you'd be wasting your breath away on borrowed beliefs.
But then I doubt you are capable of doing it, as even a scientific review appears as "corporate brochure" to you.