I don't know if it's the most unbelievable, but you are 100% correct regarding the surgeon's age. Four years of undergrad (~22); four years of medical school (+4); residency of 3-7 years with minimum of five years for surgical residency and seven years for neurosurgical residency (+5, maybe 7); post residency fellowship if wanting advance placement (+1 or 2). So, at least 34 to 35 before he hangs a shingle. Then, the likelihood of 50-60 y/o surgeons being under the thumb of a 30-something? About zero %.
The problem in this story is the nurse does nothing wrong, which makes the premise extremely unlikely.
Too soon to say. The plot hasn't progressed far enough.