Accordingly, reasonable consumers understand and expect that products marketed as “veggie” are made from vegetables, rather than beans or other legumes, grains, tofu, oil, or anything else

It basically boils down to this argument, which I don't think is necessarily true. By the dictionary definition, "veggie" can be slang for vegetarian, or if it is slang for vegetable, a definition of vegetable (as an adj.) includes "made from, obtained from, or containing plants or plant products" which applies to wheat or soy protein.