just sayin'
When the AP disconnected the PF pitched up, which eventually caused the plane to stall. Not sure why he did that, he should have just essentially left the controls alone and flown the pitch attitude at auto pilot disconnect.
But, I have no idea why the programming of the aircraft flight control systems silenced the stall warning system when in fact the aircraft was stalled. Whatever stall warning system is installed in that aircraft should have been active while the aircraft was stalled period, no excuses.