Because there's at least a possibility that the surgeon recommended and performed amputations in order to satisfy his own fetishes rather than to do what's best for his patients. As a doctor, he is supposed to do what is best for the patient, not himself.

If it is verified that he has performed medically unwarranted amputations, that'd probably result in some kind of criminal charge due to the grave and permanent bodily harm involved. The loss of his medical license would be the least of his problems.