In other words, the fore & aft moment is vastly smaller than the lateral moment, and the fore & aft resistance to failure is greater than the lateral resistance.
Believe me, if this were a fore & aft failure, there would be a huge dent in the VS that just isn't there.
Agreed. However the force could have come from any direction as long as the lateral portion of the force were sufficiently high. For example, a ditching with a significant angle between the aircraft's orientation and its direction of travel would give the tail section a large sideways kick. It need not have been a directly sideways force.