Here are numbers two and three from his point of view.  These really are thought provoking and interesting:

Possibility 2) Super-intelligent life could very well have already visited Earth, but before we were here. In the scheme of things, sentient humans have only been around for about 50,000 years, a little blip of time. If contact happened before then, it might have made some ducks flip out and run into the water and that’s it. Further, recorded history only goes back 5,500 years—a group of ancient hunter-gatherer tribes may have experienced some crazy alien shit, but they had no good way to tell anyone in the future about it.

Possibility 3) The entire concept of physical colonization is a hilariously backward concept to a more advanced species. Remember the picture of the Type II Civilization above with the sphere around their star? With all that energy, they might have created a perfect environment for themselves that satisfies their every need. They might have crazy-advanced ways of reducing their need for resources and zero interest in leaving their happy utopia to explore the cold, empty, undeveloped universe.

What do you think, is he right?  Or is there another explanation?  Feel free to comment as this is a very interesting topic of debate.

thanks to imgur for the great info