I suppose one could apply the same argument to say that it would be a bad thing for humanity to become a multi-planetary species. If it did, the same logic wou

I suppose one could apply the same argument to say that it would be a bad thing for humanity to become a multi-planetary species. If it did, the same logic would apply; once at a certain level of development, either planet could destroy the other as a first-strike. It doesn't really matter from a game theory point of view whether the planets are both human or one human and the other alien.