So who has eliminated all but UAS?
PNF.
PNF said "so, we’ve lost the speeds" then "alternate law [...]".
What was PF's initial control input, a rather robust response and result.
The airplane began to roll to the right and the PF made a left nose-up input.
initial input:
left nose-up
response:
The airplane’s pitch attitude increased progressively beyond 10 degrees and the plane started to climb.
result:
vertical speed, (which) had reached 7,000 ft/min
Did a/p drop before or after, and either way, was its involuntary loss linked to the manouver? The conditions in the cell?
From 2 h 10 min 05 (4), the autopilot then auto-thrust disengaged and the PF said "I have the controls".
As I read it, PF taking control was a response to AP/ATHR disconnect.
PNF's assessment seems to corroborate the evidence that AP disconnect is linked to loss of airspeed:
PNF said "so, we’ve lost the speeds" then "alternate law [...]".
Fixation is neurotic........and leads to accusations and unsupportable claims. Just for review, a Stall warning is not necessarily a Stall.
From 2 h 10 min 05(4), the autopilot then auto-thrust disengaged and the PF said "I have the controls". The airplane began to roll to the right and the PF made a left nose-up input. The stall warning sounded twice in a row. The recorded parameters show a sharp fall from about 275 kt to 60 kt in the speed displayed on the left primary flight display (PFD), then a few moments later in the speed displayed on the integrated standby instrument system (ISIS).
Note 1: Only the speeds displayed on the left PFD and the ISIS are recorded on the FDR; the speed displayed on the right side is not recorded.
Note 2: Autopilot and auto-thrust remained disengaged for the rest of the flight. At 2 h 10 min 16, the PNF said "so, we’ve lost the speeds" then "alternate law [...]".
The crew seem to agree with your assessment. Their actions and comments seem to ignore the first stall warning here.
Stall warning comes from the angle of attack sensors, not the airspeed indicators - so a stall warning with an indicated high speed is possible.
Note 2 : In alternate or direct law, the angle-of-attack protections are no longer available but a stall warning is triggered when the greatest of the valid angle-of-attack values exceeds a certain threshold.
Does this mean in Normal Law stall warning is coming from airspeed?