As far as instrumentation error, the stall being triggered at a 6-degree angle of attack (AoA), suggests momentary updraft. I wonder how granular those data are.
Despite a small comment about a pilot's nose-down input given, it would seem likely that it was only briefly...
As the trimmable horizontal stabilizer spent most of its time at 13degrees nose-up. I'd bet the pilot forgot that quickly, and didn't realize how it was working against him to allow him to achieve a more normal AoA in the "direct law."
The nose apparently spent little to no time at all below the horizon, which would be required to get the AoA working in the direct law.
The kind of manueuver required to regain a 4-20 degree AoA would be counter to an institutionally-trained-for-professional pilot's intuition. No pilot likes making passengers screaming their heads off thinking they're on an extreme roller coaster instead of among the leather in Business Class, but far better that than the sudden death they actually experienced.
Unlike the "diving" into the ocean mentioned somewhere, this Airbus apparently pancaked/belly-flopped after spending over three minutes in a fairly consistent position, nose high and a gentle right turn (taken by the track recordings, despite all the mention of left roll input).
Surely the other pilots were not locked out of the flight deck, were they?
The known informaiton certainly is indicative of extreme pilot error, ignorance and likely panic.
It would seem AF's pilot training will require quite a bit of increased diligence surrounding stall recovery, and the particular pilot's instructors/check pilots need their butts figuratively reamed if not summarily canned.
HF, CFII
The stall initially occurred at (going from memory here, I might be off a couple thousand) 38,000 feet. At that altitude, it doesn't take a lot of AoA to generate a stall condition.