Inertia is likely. His answer was measured - validated your concerns without admitting his rules were not necessarily supported by facts.
Main thing, though, is that he knows you are an informed patient, and was willing to discuss your options and preferences. Make sure the cholecystectomy is coded as being in response to symptoms, to make sure that part of your surgery is covered as medically necessary.
Have you made sure the anesthesiologist is in network?