it does seem weird that the PF in the RHS was not wearing any kind of seat belt,having warned the cabin crew of turbulence ahead.. i understand Airbus provide a nifty table where the yoke sits on most other aircraft
is it a possible scenario that he had the seat pushed back and was tucking into his dinner? so that when the Auto Pilot/Auto thrust clicked out he had to reach out further than usual to grab the side stick ...plus maybe with a tray full of food in the way ... apologies if this has been done to death before.. just a thought .