Interesting point (and important if we consider the author as a Tolkein critic). But I'm not sure if evil Orcs is totally inconsistent with Tolkein. If they're Elves who have been perverted mentally and physically, then they could end up effectively evil. It's also worth noting that they still have some deep senses in which they are good-oriented in the Catholic sense that Tolkein works with. I think there's a line about them essentially needing proper food, and also something about how they hate their leaders and creators. There's a sense in which they know they're WRONG.