While he may have overstated in an extremely idiotic way, most animal protein is complete, meaning it has adequately proportioned amounts of all the amino acids, while many vegetable proteins do not.

What gives animals the right to kill each other? It's just survival of the fittest. Don't get me wrong, how animals are slaughtered is repulsive, wrong, and should be fixed. But if we didn't kill animals at all, they would rapidly overpopulate because of how we disrupt the natural food chain, and complete with us for space and resources. Meat may not be necessary for sustenance, but death is just part of the development of life on earth.