Why? Well not to be confused with Jerry Falwell or anything, but the Bible says killing is wrong. Granted there are situations where you have no choice, such as war, but you should always remember that you should get no joy from it. Perhaps Sgt. York is an example that the General should draw from.
Was he talking about killing some very bad dudes that deserved what they got? Yes he was and they did. I'm sure he is a great battlefield leader, but he chose a poor forum to express his opinion.