If we're talking about the professor who says the human sacrifice was part of a "complex world view," then, yes, he is offering a form of defense. A stupid defense, but a defense nevertheless. (Stupid, in part because there isn't anything very "complex" in the idea that you have to kill somebody in order to appease a god. That "idea" can be explained in one sentence. Stupid, too, because it isn't an argument that makes the ancient Maya look any less savage, in fact it underscores their savagery. Human sacrifice is the very definition of savagery.)
Even savages have complex world views at times that fact does not justify anything. And a society as advanced as the Maya and Aztec is anything but savage. Their urban development was far ahead of anything in Europe at the time. Not to mention their astonomical knowledge.
Correctly describing Marxism as a complex economic theory does not make it right or moral or anything else.
If you actually study the theory behind the Nazi persecution of the Jews it is very complex far more than merely blaming the Jews for Germany's problems. And stating that it is complex is in NO way a defense of mass murder.
But I understand how desirable it is for some to make knee jerk attacks on the Leftwing scum who populate our universities. One can hardly find a more loathesome crew.