You do need to evaluate the options for self-evacuation. If it had just been a simple sprain, with a good support bandage and some help, she probably could have self-evacuated. In this case--horrific sprain/dislocation/probable fracture, long distance, difficult terrain--you definitely would have called for help--as you say, she couldn't have walked out even with assistance.

Nature of injury, distance from the trailhead, quality of terrain between accident site and trailhead, weather conditions (storm coming?), your backcountry experience--all play a part.

Certainly with two WFAs and an RN, you were far better equipped than most parties both to deal with such an emergency and to know when it's time to "push the button."