From the Wikipedia article on Greger, it looks like he may be cherry-picking his evidence or overstating his claims in some cases. Speculation, but that might be a reason people would disagree that nutritionfacts.org is a good source:
> Retired physician Harriet A. Hall, who is known for applying critical thinking to health claims, has written that, while it is well accepted that it is more healthy to eat a plant-based diet than a western pattern diet, Greger often overstates the known benefits of such a diet as well as the harm caused by eating animal products (for example, in a talk he claimed that a single meal rich in animal products can "cripple" one's arteries), and he sometimes does not discuss evidence that contradicts his strong claims.
Well, I suppose. Ariely has a good video on that people getting irrational as the topic moves closer to the body[0].
It's still pretty ridiculous given that just about everyone else is replying with their unsourced opinions.
And that's basically one guy whose critique is "he's a bit too enthusiastic about the plant-based diet." Given how attached people are to meat, that's hardly a strong counter-argument.
If the guy turns out to be a quack after all, I'd like to know why, not just be passive-aggressively told I'm wrong.