I assume here that excursions in measured AoA outside the S/W threshold below 60 kts and on the ground would be transients
Not necessarily. e.g. On a parallel taxiway to the runway, whilst heading towards the holding point in a stiff breeze will cause the vanes to align 180 degs away from zero. Hence the need for the 60 kt logic when on the ground.
Unfortunately no one ever imagined anyone could pull an aircraft into such a stalled AoA without realising it. However this crew succeeded. But why were they so confused? Intermittent warnings didn't help the Captain to diagnose the problem. One tends to think that particular problem has been solved when the warning stops, and so move onto the next problem. e.g. Why are the altimeters winding down to electrical zero?
Edit. Hi Owain. Changed " didn't help the crew to diagnose" to "..Captain .." since the two FOs hadn't a clue between them.