It says nothing more than that some evil people may also be vegetarians. The question itself is based on an invalid syllogism: Hitler was a vegetarian; Hitler was evil; therefore vegetarians are evil. Stalin ate meat and was himself no angel. He was responsible for the deaths of millions of innocent people. What does that say about meat eaters? Just as we cannot conclude that all meat eaters have anything in common with Stalin beyond meat eating, we cannot conclude that all vegetarians have anything in common with Hitler beyond vegetarianism. Furthermore, it is not certain that Hitler actually was a vegetarian. And in any event, the Nazi interest in reducing meat consumption was not a matter of the moral status of animals but reflected a concern with organic health and healing and avoidance of artificial ingredients in food and pharmaceutical products that was linked to the broader Nazi goals of “racial hygiene.”
Another version of this question is that since the Nazis also favored animal rights, does this mean that animal rights as a moral theory is bankrupt and attempts to devalue humans? Once again, the question is absurd. In the first place, the question is based on a factual error. The Nazis were not in favor of animal rights. Animal welfare laws in Germany restricted vivisection to some degree, but they hardly reflected any societal preference for abolishing the property status of animals. After all, the Nazis casually murdered millions of humans and animals in the course of the Second World War, behavior not compatible with a rights position, human or otherwise. It is no more accurate to say that the Nazis supported animal rights than it is to say that Americans support animal rights because we have a federal Animal Welfare Act.
But what if, contrary to fact, the Nazis did advocate the abolition of all animal exploitation? What would that say about the idea of animal rights? The answer is absolutely clear: it would say nothing about whether the animal rights position is right or wrong. That question can be settled only by whether the moral arguments in favor of animal rights are valid or not. The Nazis also strongly favored marriage. Does that mean marriage is an inherently immoral institution? The Nazis also believed that sports were essential to the development of strong character. Does this mean that competitive sports are inherently immoral? Jesus Christ preached a gospel of sharing resources on an equitable basis. Gandhi promoted a similar message, as did Stalin. But Stalin also devalued human beings. Can we conclude that the idea of more equitable resource distribution has some inherent moral flaw that taints Jesus or Gandhi? No, of course not. We no more devalue human life if we accord moral significance to animal interests than we devalue the lives of “normal” humans when we accord value to certain humans, such as the severely retarded, and prohibit their use in experiments.