Discrepancy
GerardC
There is an additional circumstance. Without discrepancy among the ADRs, but with a drop or gain of >30 knots with the concurrence of all three, the automatics drop out. This is sudden, and would seem to relate to the need for immediate manual control, as in WIND SHEAR.
Turbulence is the prime candidate for even a conformal change in airmass speed (or direction, sensed as the 'same thing' by the a/c).
The sudden loss of a/p is consistent with the lack of a 'run of the mill' UAS.
It also argues against ICE having any impact on the Probes. Beyond this, airspeed variance of this order would also be associated with OVERSPEED PROTECTION.
Overspeed (a/c reaction to) explains the fixed position of the THS in the climb.
Similarly, a possibility of this sort explains why the speeds did not become discrepant until after the loss of a/p, and the degradation to AL2.
My understanding is that with WIND SHEAR, the a/c remains in NORMAL LAW. This also would explain why, if so, the PF was convinced he was in NL well into his climb, and felt safe in Pulling aft stick.