ATHR disabling (by holding disconnect buttons for more than I-forgot-the-exact-number seconds) was planned but not executed. Alpha floor didn't activate because it's inhibited below 100 ft per design, in order not to spoil the landing.
Why should a line pilot who only has access to FCOMS indulge in manoeuvres which even the test pilot did not, in radically different aircraft?
Showing off. Careless planing combined with sloppy execution. Chances are they never meant to fly that low, which does not imply it is acceptable to make high alpha pass with planeload of passengers at 200 instead of 20 ft.
Also, I recall something about Airbus fbw going to "direct law" at expected landing radar altitudes, and that this mode gives the pilot direct stick-to-pitch control.
Some widebodies stop autotrim, narrowbodies add automatic pitch-down command to facilitate the flare but going to direct law happens only with gear extension when aeroplane is already in alternate law and that was definitively not factor here. Aeroplane was totally sound just before controlled flight into trees.