Final answer:
The best course of action for the physical therapist is to apply moist heat and perform glides in the opposite direction to the direction of restriction.
Step-by-step explanation:
The best course of action for the physical therapist to make when the patient complains of severe pain and irritability during a grade 2 inferior glide on the glenohumeral joint is to apply moist heat and perform glides in the opposite direction to the direction of restriction. This approach can help reduce pain and improve the patient's condition.