I guarantee you that the Kinect does not transfer that kind of information to Microsoft since it will be caught and there will be outrage.
Obviously, if they were planning on using the device to spy on people, it'd be for extremely targeted operations, activating monitoring mode only for certain people, and therefore not likely to be discovered.
Why not send the previously collected bursts while you're playing games? Remember the big stink about the last generation of games needing to be online originally? well, we're already all doing online games and services (netflix, Facebook, twitter) on the TV anyway. The XBOX data can go wherever it is the online data servers are, and distributed man-in-the-middle-style from there to MS, and thus, the NSA. Just sneak a bit at a time into the game / video / DLC bursts and encryption will hide the rest.