Earlier quoted context omitted.
I've always found that alien argument weak. Humans pass a threshold given that we have self-awareness. None of the animals we eat for food do. If aliens were advanced enough to travel earth hopefully they would have a similar set of ethics. Of if they were just warmongers/conquerors it wouldn't matter.
How do you know other animals are not self-aware? Is self-awareness a criteria for not being killed and eaten? Is it not pain and suffering that really matters?
Pain and suffering are irrelevant given we can kill animals in a humane way. Only the right to life is relevant.