I'm not following. The universe is unbelievably vast, and likely has many, many more magnitudes of intelligent species out there than we have had cultures down here on this one planet.

I don't want to get into arguing Drake's equation here, but if you accept that aliens exist, then you're granting that there's a lot of them; it makes no sense why we would be, e.g., one of only two intelligent species in the entire universe.

It's an argument against the "naturalness" or inevitability of the discovery.

It may be wrong, but "aliens" is not a response to it.

If I'm understanding correctly, the sticking point here (and in most of the thread) is people arguing about different things. Some people are saying the discovery of Go is inevitable (certain?), some are saying it's likely (but not inevitable), some are saying it's possible (but not likely).