Basic airmanship/CRM or just plain bloody common sense. One pilot flies the aircraft and the other's primary job is to MONITOR that guy's flying - irrespective of the phase of flight or what problems may have occurred.
The lack of action from the RHS could be due to any number of reasons but I will never allow anyone to fly me into the ground without trying to do something about it. Unfortunately for a lot of people this F/O did just that. The investigators really need to examine the training methods and attitudes of this company in minute detail to see exactly what they do. A lot of people dead for no good reason.