So Billy is promoting a coup.
That is my impression from reading that long list of tweets. Billy and others think Kelly and Mattis should “do” something. I think they miss on both the Generals. They are both on Trump’s side with differences. Trump used Mattis, in particular, for a particular job that Mattis was highly qualified for. He did that job and was not needed any more. Different qualities were then required. Kelly quit in a snit and now seems to regret it.