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It might help to know more about the reasoning of both the son and the surgeons. If the son's answer was not motivated by the patient's best interests (like, amputation would be Revenge for some past grievance), then there's less reason to listen to him.
Anti-Advice is related (get someone's advice, do the opposite), but usually reserved for characters who are consistently so inept that they always arrive at the wrong answer.
Apparently the reason the son preferred the safer treatment was that it was safer, and the father had previously said that as long as he's alive they (father and son) have hope for a better life. The doctors ultimately conclude that without a right arm the father's ability to provide for the family would vanish. (This is an immigrant family).

A man is hospitalized. While he's sedated, a decision must be made if it's better to do the safer surgery of amputating his arm ir the riskier surgery which will avoid that. The only relative the patient has is a son who is too young to serve as a medical proxy; however, since the staff members don't know the patient, they talk to the son to get an idea what the patwould have preferred had they been able to ask him directly. The son says that amputation is the right answer, but the surgeons ultimately decide—from the overall information they got from the son—to take the riskier surgery.