Notice his article does not contain the words "fun" or "enjoyment." That's not his field. Instead it's "the pattern of activity you want."
"...at this point, younger gamers will raise their arms above their head, leaving them vulnerable."
His theories are based around the work of BF Skinner, who discovered you could control behavior by training subjects with simple stimulus and reward. He invented the "Skinner Box," a cage containing a small animal that, for instance, presses a lever to get food pellets. Now, I'm not saying this guy at Microsoft sees gamers as a bunch of rats in a Skinner box. I'm just saying that he illustrates his theory of game design using pictures of rats in a Skinner box.