An alternative view
The accident report and much of this debate has focused on UAS in that the crew failed to understand that situation.
However, I don’t recall the following alternative being considered.
The crew had not detected the UAS situation, but with ADC dropout/changeover the (unwarranted?) stall warning was taken as real. The PF commenced stall recovery, except erroneously applied power and pulled up with the intent of using the alpha protection – typical GPWS / windshear recovery – perhaps a stall recovery technique as perceived from training or other bias.
This assumes that the PF did not comprehend that the aircraft had reverted to Alt Law, even though it was alerted and called by the PNF. Thus there was no appreciation of the loss of stall protection and actuation of stall audio. Much of this behavior could be consistent with the aspects of surprise – confusion. This too could encourage the choice of an inappropriate manoeuvre, as could weak training, or biased understanding of the control system – sales talk / social chat pages.
It also questions if stall recovery in normal law was ever taught this way or discussion of ‘the aircraft won’t stall’ dominated the GPWS / windshear recovery training.
Subsequently in the event, when the aircraft stalled, the PF was further confused by the true stall warning; – according to him he had been flying the ‘correct’ maneuver.
Nose down stick stopped the warning, but nose up – the assumed correct recovery, gave a warning.
After the AoA cut out, the situation reversed. Moving the stick forward / lowering the nose, gave a stall warning (AoA reactivated), but nose up stopped it as the AoA cut out. This was the reverse of conventional logic, but supported the erroneous nose-up to recover course of action as being correct, as this stopped the stall warning. Hence there were many comments of confusion.
Thereafter we have history. This supposition identifies the difficulties of ensuring correct context in training, and correct recall in real situations – situation awareness. Also possible areas where the use of technology opens additional error paths – a choice of recovery techniques depending on the situation / control law; either a pull up in normal law using the control protections (GPWS / windshear recovery), or in alt law, when the aircraft might be stalled, requiring different and more circumspect action.
This is not to say that the technology is at fault, but more likely the human choice of how to use it (training / operations / regulators / manufacturers); and that this choice may increase mental workload in situations where quick clear thinking is more likely to be required.