Originally Posted by
jcjeant
Why (or how) THS will stay
(nothing move even 1°!!) full up to the end of the event ... when we know that
nose down inputs were performed ... 
How you explain this this
contradiction (for me) in the BEA note ?
Very simply.
The nose down inputs were transient. They were not of sufficient size/duration to cause the THS to move.
It's a pity that the stall warning sounded again after they made the correct (ND) input.
One of many 'pitys'. It's an complex and interesting human factors issue. My feeling is that if the aircraft doesn't have valid input then it is preferable not to output (so it turned off the stall warning when the AoA went out of range). Otherwise you risk GIGO. At the end of the day, if the aircraft cannot rely on its own sensors, the aircraft has to hand over to the pilots and expect them to act correctly.
It certainly needs a rethink, though I suspect this functionality was specified by a multi disciplinary team which included test-pilots. Not saying that it cannot be improved on of course. And there is no evidence to suggest it is the a primary cause of the accident.