Lemurian,
There is nothing on those pictures that would tell you anything about "sideways forces"
As a matter of fact, until we see the other side of the fin, evidence points towards a longitudinal breakage : the base of the rudder is broken, hinting at possible compression stresses, whereas the forward part of the fin base shows a more cleanly accomplished separation, this time indicative of tension forces.
With these observations, I could deduct that the moments that caused the fin to shear from the fuselage were directed aft, meaning the tail hit the water first ; an observation that could lead me to claim that either the fuselage broke in mid air in several parts or the entire aircraft was in a high pitch angle on impact...and still hit the sea tail first.
As an engineer responsible for designing connections between steel components (and occasionally composite materials), I believe that I am well qualified to comment here.
Here's my reasoning:
The total force involved in breaking off the VS is pressure x area.
The frontal area of the VS is very, very small indeed (there's a reason for that - think about where you want as little drag as possible).
The lateral area of the VS is huge in comparison (there's a reason for that too, when you think about it).
So which of these is going to produce the larger total force?
Next, we move to the geometry of the connection to the fuselage. 2 lines of bolts running fore and aft, 3 bolts per line. The side to side distance is significantly less than the fore and aft distance, so the resisting moment is also far less.
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.
FBW