I think that your airline/operator has a certain problem with SOPs. For both major operators that I've worked for, SOP was that BOTH pilots must have heard the clearance, and agree with each other that they've both interpreted it identically.
If only one pilot has heard it, then "say again clearance" to ATC is a requirement. If one pilot is absent from the cockpit, e.g. at the loo, the remaining pilot at the controls is expected to follow the new clearance, but request confirmation from ATC upon the other crew member's return.
411A, I agree with you in principal, but I doubt that this prat's problem could be fixed in the Simulator, methinks some other form of management directed "motivation" would be in order.
A good
SOP will greatly help with problems encountered with the
SOB you were flying with!
Regards,
Old Smokey