I think it unlikely that it would have been totally an updraft. But if it was the autopilot would maintain altitude until the speed increase approached Vmo/Mmo, then the automatic overspeed protections would raise the nose to control speed. This overides sidestick input from the pilots and MAY trigger a cascade of events ending in a high alpha attitude.
There are other scenarios involving no sensor fault but an unhappy combination of wind change, temperature spike and high vertical speed approaching a higher target altitude which can result in a low energy/high pitch situation.
Writers without Airbus experience should appreciate that the flight control programming is biased towards load relief and structure protection, hence the attitude constraints and the urgency with which overspeeds are "corrected" by the software.
Additionaly, from my own simulator training I suspect (but have not found mention in any manuals) that when a protection gets triggered it stays active until the original condition has been corrected, so that an overspeed protection will overide the stall protection from activating, and vice versa.