Anyone who has looked at an unrestrained vane-type AoA sensor on a parked aircraft on a windy day will have seen the vane wandering all over the place. On take-off, as speed increases, eventually the forward component of airspeed is enough to straighten out the vane, so by 60 kts it IS reading (something related to) incidence. At some speed below 60 kts its reading means nothing. We don't want spurious stall warnings during the t/o run (or even on roll-out) so the system ignores the AoA below 60kt. All very logical until we hit this scenario. Perhaps the "ignore AoA under 60kt" rule should only apply when WoW switch is on?
It seems agreed that the flight controls were sustaining a nose-up attitude and no one has (yet !) suggested that this was not related to a back-stick command. So either (a) the crew were fixated on the "overspeed" scenario and maintained their "pull-up" input, ignoring the (intermittent) stall warnings (and pitch attitude?), believing they were trying to recover from a dive, OR under pressure they "overlooked" that the degraded control mode/ sensor input problems no longer gave a safety protection that full back stick will not be allowed to stall the aircraft?