Catherine Wagenseller was a nurse at Scottsdale Memorial Hospital and an employee at will. While on a camping trip with other nurses, Wagenseller refused to join in a parody of the song $$Moon River,$$ which concluded with members of the group $$mooning$$ the audience. Her supervisor seemed upset by her refusal. Prior to the trip, Wagenseller had received consistently favorable performance evaluations. Six months after the outing, Wagenseller was fired. She contends it was because she had not mooned. Is it legal for the hospital to fire Wagenseller for this reason?