The sole reason vegetable eaters find eating vegetables justifiable is they attribute no moral value to the lives of non-animal life forms.
Animals do not have similar food-providing mechanisms. When you eat an animal, or part of an animal, it'd dead. It doesn't grow back. It wasn't designed to.
All nutrition comes from plants (or the microbiology around them). All protein comes from plants. Anyone who equates the barbary of eating animals with eating plants is choosing to deceive themselves and others.