If he is bad, why does Bannon support him?
Bannon is great thinker, but also a crazy alcoholic egomaniac. Often right on things, but often extremely dumb, like inviting Michael Wolff into the White House whereupon he completely shat on Trump.
Greitens is one place where Bannon is being blinded by Greitens willingness to show up on his show and stroke his ego. Kind of like Trump, Bannon has a brilliant vision on big issues, but then gets wrecked because of poor judgement of character.