I've thought about this more since yesterday, and I agree. With the information in the book, a reader would conclude that Rorschach was closing in on Dr. Manhattan's "evil plan" and went to Antarctica to stop him, and failed trying. So his journal only adds to the lie that he wanted to expose. It reinforces the lie! So no, I don't see it as some sort of victory for Rorschach. It's just one last posthumous kick-to-the-guts for the guy.