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
As a writer with Airbus experience, i can say that you very accurately described what i criticise since many years!
Reading what i have enlightened makes a scary story.
In short, the two recent Airbus fatal accidents have shown that whatever the protections wanted to protect (load relief and structure protection) has resulted in the exact opposite!
We can now wait for another lengthy and overcomplicated analysis of what exactly happened at which exact moment, what computer action went wrong and what exactly the crew should have done out of memory to counteract the overwhelmed and misguided program, or .... we can wait for a speedy and effective correction of the programming and design.
My bet is on the earlier in a years time and nothing on the second.
Waiting for the next Bus excursion.