I eat animals, but I'm not convinced by your argument. We're omnivores, so it wouldn't be unnatural for us to survive on plants. In fact, there are cultures that do just that.
And while I understand that this is an appeal to nature. It doesn't matter whether this is good or bad; it's necessary. Anybody making the claim that it isn't is ignoring collateral mentioned in the article, and is really just leaning on one side of two different, but albeit very important classes of organisms. I'd prefer to treat them fairly. Eat them both!