It makes him look like the smartest guy in the room during the entire campaign and beyond.
And knowing that Trump always does the opposite of what his advisors tell him, because he doesn't like being told what to do, Bannon will position himself as a man who should be listened to, as a person who had ideas that were not heard and not utilized by Trump, the man who was elected to "Make American Great Again" and has failed to do so.
Bannon is attempting to give himself a reset. It will work with the poor working class whites who don't realize that he is using their stupidity (racism, xenophobia, sexism, homophobia) against them in order to secure their vote, and further fukk them in the ass.