That right there is sufficient, in my mind, to warrant dismissal.
In the article it says Rosenstein hired Mueller without first discussing with Sessions yet Sessions feels loyalty to quit if Rosenstein gets fired then to resign to help his President. He had a duty to tell the President he would have to recuse himself which would have given his President the option to appoint someone else.
So his loyalty is to Rosenstein and not the President.
Sessions was a purposeful snake!!!!
Sessions has good reason to fire Rosenstein and should do it himself.
Maybe return the favor of RR buying you dinner, and take him out to dinner.
Then eat his lunch.