The very first thing you learn in asymmetric training is "Dead foot, dead engine".
I'm not so sure that saying is used to help you decide which boot to move, rather than help you diagnose which engine has failed from the resultant rudder deflection! If an engine fails you move your feet to stop the yaw visually and put the ball in the middle all with the wings level. In this case that should have been right pedal. Once you've regained directional control you use the "dead leg" (in this case left) to confirm the loss of thrust is on the left!
That said, this accident was the result of some inept aircraft handling combined with equally poor CRM.