That sideways force could have happened towards the beginning of the sequence (as in the AA A300 accident), or at the point the VS hit the water, or any point in between. Time will tell.
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.
But of course, I won't make that kind of deduction for I'm one of those who would be very careful with too-quick conclusions and await further evidence.