villas
The French report, page 35:
12h 46' 26'' CDB "Bon Je vais bien la debrayer l'auto-manette." (Google translate = "Good I'm fine to disengage the auto-throttle"). Radio Altimeter shows 40 / 50 / 40 feet.
The Captain is aware the auto thrust is disconnected, yet he doesn't apply TOGA thrust for another 10 seconds with a plane full of passengers. Incredible!
He did not seem aware of this that is why he was surprised by the lack of alpha floor response and moved thrust levers manually.
I think you are right. It is the best explanation so far.