The way the door is wedged in the elevator i think he did a very good job. Probably no pitch control. Mooney's are a strange beast with a all moving tail for trim, perhaps lucky to be in a Mooney. Landing flapless to prevent further pitch changes and at speed, gear at last minute, all added up to a safe landing.
Non of us know the reason for the door to become detached, just perhaps next time we all take more notice of baggage doors.
I remember watching a piano wire on a PA28 cowling hinge creeping forward to the prop. in flight.