I use to work for MS a long time ago and I can safely say that this guy will be on a very hot plate. MS do not allow their employees to make any statements about MS that has not gone through proper channels. This type of stuff gets you fired in a heart beat so it will be interesting how this all turns out. MS does monitor twitter and other places where employees can express their opinion and its strictly taboo to do what this guy has done. Even if he is only making fun of people and enjoying the ride, from personal experience, this will not go over well.
I feel sorry for the guy if he does lose his job over somethig like this. There are some people at MS that do not read those thick policy documents but since it is a responsiblity of the employee, it will not stop the hammer.