It seems to be saying that the only reason he said that was to create disscusion. I doesn't seem like he really meant anything he said, he was just posing a hypothetical scenario. That is a common thing for history teachers to do, it helps the students relate to the material better. But I agree that he did go over the line with it and does deserve some kind of punishment for it. I am not a school administrator, nor do I know anything about what they could do to him, but something is in order.