I am not sure if he is implying that existence is conditional upon whether or not humanity as a whole recognizes something exists, or whether one is only capable of existing through experiencing their own consciousness (Kant's idea about how our existence is based on our ability to perceive a reality, kind of). In other words, whether or not aliens are conscious is irrelevant to the argument, as is orangutans, as is you believing you exist (because for all I know, life could be a figment of my imagination). At least that's how I interpreted the debate.

But then, coincidentally, I was just talking about this at dinner tonight. The general consensus was that this is unprovable and since it is unprovable, we might as well act as if it isn't true (because it adds another layer of complexity rather than just assuming there is an existence outside ourselves) by Occam's Razor. That's the thing with all these philosophical debates. They are usually unprovable, and are therefore essentially worthless (if we go by scientific standards of logic and truths).

P.S. this thing is telling me "unprovable" isn't a word, but because my brain is dumb right now I can't think of the word for it, and unprovable is pretty clear on what I mean.