BJ-ENG, figure the tail section hits the water. Is it going to show the same ability to push into the water that the fuselage would? If not, what happens? The tail is pushed up relative to the fuselage. The nose of the VS can't easily go down. So the VS is pried loose from its mountings. The first thing it does is fly upwards, maybe a little forwards.
The actuator arm hints that as the VS came off the plane the rudder was off to one side at least somewhat. So the wind catches it and it's pushed backwards relative to the plane. The plane hits the water and doesn't stop its forward motion instantly. The VS flipped into the air will stop rather suddenly as it turns in the air and wind above the plane. I picture it flipping upwards, twisting like a playing card tossed into the air, and falling behind the plane by anything from a few feet to several dozen feet by the time it hits the water.
That would easily account for no dings on the VS, its unfortunate "nose job" at the front, and the particular damage to the mounts.
I don't see it "breaking off" from momentum or sideways pressure. I see it being pried off by the separation of the tail from the fuselage in a relative rotation upwards as the tail peals away from the pressure vessel rotating around a point a little aft of the VS's nose.
Edit: Of course, it's not as if I haven't been trying to explain this hear for the better part of two years now.... {^_-}
{^_^}