Hyperveloce:
why don't the middle and rear fasteners of the VS with the related fragments of the fuselage hoop frames (who suggest a forward motion & slight twist) show this strong compressive structural effect ?
That the connecting brackets between the floor and the walls were bent...
Here is my take. The VS is a large and comparatively massive bit sitting on the end of the tail, with a small connective cross section facing downward against the tail cone. With strong vertical deceleration, the VS is going to compress against the upper wall of the tail cone and in this case, probably punch through, breaking the body around it. The forward deceleration then causes the VS to continue through the air forward relative to the rest of the aircraft.
A slight leftward twist in the airframe would affect damage on the VS, and might affect its tragectory after departing the airframe. However it wouldn't affect the rest of the scenario substantively.
I don't think a forward failure would necessarily be seen from an in-flight separation because of the aerodynamic forces involved.