Aside from all the other objections, this brainstorm doesn't even achieve the stated objective of reducing land use. The thing is 2.2 miles in diameter. Leave some safety margins at the edges, and we're talking about a square of land about three miles on a side.
I did a little research and as I suspected, Seattle-Tacoma Airport's longest runway is 11,900 feet, or 2.25 miles -- and even counting the parking facility, that airport is not 2.25 miles wide. Square footage-wise, we win, and we weren't even trying! That Sea-Tac runway must rank as giant, too, because when you come in on a 747 or A380, you usually see a lot of runway go by beneath you before you touch down. And, sure enough, even the A380 -- destined to soon be as much a dinosaur as the 747 -- only requires 9,020 feet for takeoff, and much less for landing. (I'm sure pilots have some sort of saying about, "No such thing as too much [something], [something], or runway," but those are the requirements, and the A380 is the civilian airplane with the longest runway requirements at the moment. (I don't know about military planes, but since they are required to not mind a bit of a rough ride, I imagine they have ways of managing "shorter than optimal" runway lengths.)
I rather suspect this "plan" from the "Netherlands Aerospace Centre" may be the product of a bunch of engineers hitting that ol' Dutch wacky tabacky to excess.