If the citation from Airbus is to be believed then your analysis is not correct. Airbus says the angle of attack increases. I always envision relative wind as a vector that points towards the aircraft and a sudden shift as the result of a strong down draft would increase the angle or move the relative wind vector lower or in a counter clockwise direction, increasing the angle of attack.
Angle of attack is the difference between the wing chordline and the relative wind. If you move the relative wind downward as it strikes the wing the angle increases. There is some reaction by the aircraft because as the aircraft sinks that has the effect of reducing the relative wind angle. I am not sure in a wind shear situation if that makes up for the updraft or not. This type of question is sort of outside the normal aerodynamic text book explanation.