Tell your RSO to go back to reading Soldier of Fortune.
Yes, a pelvic hit can be an option, but as the guy is falling down he is still pulling the trigger.
A COM may not stop him from pulling the trigger either, but I will prefer to take this shot over the pelvic shot.
Usually the pelvic shot is taught as an alternative to the head shot in the "two to the body, one to the head". Instead it would be "two to the body, one to the groin".