It's kind of an ironic and funny comment. See, if they are intelligent, they wouldn't want to come here in the first place, seeing as this place is such a mess. So if you believe in the theory that there is intelligent life out there (based on whatshamaxcalled it's equation, or whatever), then them not appearing here is good evidence of that they are very bright.
Kind of like the Chinese, way back when Europeans were basically rolling in their own fecies. They had nice big ships to sail the world and what did they find? China was a hell of a lot better, and they went home! When Europeans found out that China was a hell of a lot better, they built their own ships and set out, ruining just about every place they set their foot on!
Maybe it's best we don't have light-speed travel yet.