Was he a good cop? Depends on what you mean by that. He was non-violent, and conscientious, and principled, and enforced the law with unusual accuracy and precision — but whether his superiors were satisfied with his performance, I can't say. I'm inclined to imagine that they found his resistance to what he saw as bad, stupid, or unethical policies inconvenient, and his enforcement of what they saw as trivial violations tiresome. I'm inclined to doubt that his superiors appreciated his intellect.
Are we really sure that it's unreasonable to reject an applicant because he is too smart, if it creates a dissatisfied officer and dissatisfied superiors?