Is Bannon's role there primarily to
listen, or to give advice/formulate policy? I'm not sure how anyone on the outside can possibly know that, and if it is the former, I cannot possibly see any harm. Also, from the article:
I fear that it will have a chilling effect on deliberations and, potentially, diminish the authority and the prerogatives to which Senate-confirmed cabinet officials are entitled.
If he's thinking that Mattis or Kelly are going to be shrinking violets and not express their opinions because they are "intimidated" by Bannon....well, I think Mullen may wish to rethink that. We've already reportedly had one instance where Bannon tried to order Kelly to do something, and Kelly told him to pound sand. Pompeo isn't exactly a wuss either, nor General Flynn, or General Dunford for that matter
That is one virtue in Trump appointing a lot of strong personalities to his NSC. Groupthink and a reluctance to speak up is not exactly going to be a problem.