Hi jcjeant,
The BEA Update is written in plain language, and time-markers are very limited. There is much room for interpretation (that is, ambiguity). That is why many of our best contributors here are either silent, awaiting the full data, or contributing but rarely.
You have chosen to interpret it in a way which supports your pre-conception that the upset was likely to have been caused by a fault in the Airbus FBW system. Good luck to you. As you would expect of an ex Airbus skipper, I look at it from a different perspective: was it weather, system fault, or pilot mishandling in difficult circumstances; or some combination of these factors?
Remember, the BEA states that, after the AP disengaged,
"the airplane began to roll to the right and the pilot made a left nose-up input",
but it doesn't say how long the nose-up input lasted.
I think the clue lies in the next paragraph, dealing with the initial climb, of which you have only quoted the first part. Here is all of it:
"The airplane's pitch attitude increased progressively beyond 10 degrees and the plane started to climb. The PF made nose-down control inputs and alternately left and right roll inputs. The vertical speed, which had reached 7000ft/min, dropped to 700ft/min and the roll varied between 12 degrees right and 10 degrees left. The speed displayed on the left side increased sharply to 215 kt (Mach 0.68). The airplane was then at an altitude of about 37,500 ft and the recorded angle of attack was around 4 degrees."
[my highlighting]
So, a likely interpretation is that the PF's nose-up input initiated the climb by increasing pitch to above +10deg. (You may disagree.) That is an extraordinary attitude at high altitude. He may have ceased nose-up inputs at that point, but the new pitch attitude produced a climb VS of 7000ft/min. At that rate, it would only take about 15 seconds to get to the next point, where the PF made his short-term nose-down input, causing the reduction in VS to only 700ft/min with an AoA of +4, which was just below the stall AoA.
At this stage, the situation was already very serious and very tricky to stabilise, and it is easy to criticise with armchair hindsight. However, had he maintained some forward stick for a bit longer, a descent would have started and the aeroplane would not have stalled. His altimeter should have been not more than a few hundred feet in error, so he would have known he was too high. A gentle descent with the nose somewhere near the horizon would have been a step in the right direction. The pitch-up tendency caused by the selection of TOGA thrust would have been countered by the FBW system applying down-elevator, backed up by the THS.
Unfortunately, according to the BEA, the PF's next pitch commands were nose-up. The reason for that is unclear, but that is what led to the stall.