He was also raised to believe that being a Death Eater was great, Voldemort was a great guy to work with, and killing in the name of blood purity would be glorious. If he doesn't really hate them for being Mudbloods then it's even less of a change of heart. He hates Hermione for being Hermione, but is able to hide behind the idea of her blood mattering. Now, maybe he will just stay the same and keep his mouth shut, but that would also mean he spends the rest of his life in denial, not facing his real feelings. He could definitely end up that way, but what I liked about his story in HBP is it seemed like it was interested in forcing him to give up some illusions and grow up. So even if he clings to his old beliefs, will he be able to do it the same way he did when he was 12?