You keep missing the fact that he still had 3.5 degrees of stall margin remaining at the same time he held full aft stick. And CLmax is at a little higher alpha than AlphaMax.
Nobody disputes that Sully should have had more airspeed. The fact is he didn't, OK, pilot error, we got it. Enough already: Not the topic here. ... The fact is automation saw fit to deny just enough remaining alpha to get the plane to a better deck angle for ditching. That also would mean a lower impact speed could have been obtained. Look into the other several A320 accidents in the past where alpha protection in flare occurred (mentioned in this thread to show the history).
I'd like to find out who thinks its a good idea (like Airbus does) to allow the fly-by-wire to give nose down commands when there is still margin to stall in flare? And what possible reason would there be to limit max lift that way down low in flare?
Again, I do think Airbus's alpha protection is fine above flare altitudes, just not below around 100 feet.