Those who have read up on decision theory will be familiar with the term superrationality and notice that you are misusing the term.

Superrationality involves assuming that other people using the same reasoning as yourself will produce the same result as yourself, and so you need to decide what is best to do assuming everyone like yourself does it too. That does indeed seem to be what eli is talking about: you support the existing system, knowing that if you think it's a good idea to support the system, so will other people who think like you, and the system will work.

You seem to be confused either about which piece of literature is being discussed or about the target audience of said piece of literature.

I don't think he's confused. While Eliezer's fanfic isn't children's literature, the fact that Harry is a hero with plot armor is not something Eliezer invented; rather, it carries over from the source which is children's literature.