The fuselage at this point might be angled inward enough toward the low wing immediately before the snap-roll that the rudder would be rendered ineffective in holding the tail position in its alignment with the nose. Almost exactly at that same moment when this is occuring the snap-roll begins to occur rolling the jet toward the high-wing side. In essence the high wing leading edge was pulled out of position enough to cause separation of airflow from that high wing. Given the pulling of the wing out of position, the canards probably functionally failed as well.