I don't think the FO did that because the captain would have stopped him if he did. Would any captain let his FO do this? I wouldn't. We had an A300 have out of control rudder movements landing at MIA and both pilots felt they were going to crash prior to this event. They went around and regained control. The FA's in the back would be beat up by the rudder movements.
NTSB has political pressure to blame the pilots, not the manufacturer, so blame goes to the low money people.. That is my opinion.
My friend by the way was the FO in the MIA incident.