That’s what I was thinking too. I think at this point, we’re pretty darn sure there’s no alien civilization on the moon. For there to be one suggests very possibly it’s purposefully hiding from us. That’s the scariest idea, I think. If it’s just a little further away, we can assume that they aren’t trying to hide. But the moon is too close and too well studied for a civilization to be there without likely some advanced method of hiding.