It's pretty cool the way he set up his tracking rig on that high desk. Since he's only recording himself in there, it makes a lot of sense to have a higher desk so it's more comfortable to manipulate the DAW from a standing position. I wonder how much of his guitar sound was POD before.
Yes, its unusual to stand while tracking, but I guess its better for your back
He also tracked singers that way in the back of the room.
Here's Dan Swanö singing and at 0:29 you can see Arjen standing there recording.
maybe its the fact that he's (Arjen) like 6' 10" tall (2.03 meters) ... maybe its just more comfortable to record like that instead of sitting at a desk trying to fit those giant legs under it