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.)