I think this teacher is more nihilistic than anything. If we teach the Holocaust then we have to teach the other point of view. It may be evil from a Jewish perspective but it makes perfect sense through Nazi eyes. So you see there is no truth, no reality, in the end it’s all just stories and feeling.
I’m rereading Mere Christianity. In his discussion of moral good he discussed what the world would be like if there were no absolute good. This sort of encouragement to look at both sides stuff is one of the rotten parts of our culture.