I think this is something that Harry is going to have to learn in Book 7. If even Sirius, who is not known for his wisdom, can say that the world isn't divided into good people and Death Eaters, Harry is going to have to learn about grey areas. I think he is more mature than CAPLOCK HARRY of book 5, but he's not there yet. His unrelenting hatred of Snape and Draco has done only harm.