Session had nothing to do with it he had recused himself it was Rosenstein that did this and it is inexcusable that he didn't do his homework better about Mueller's ties with Comey. Whatever my feeling about Trump in all fairness this is a definite conflict of interest. How would you like to be hauled into court only to find out the judge was a long time buddy of the man who accused you of a crime? Somehow I don't think his reputation as a stand up guy would  leave you with complete faith in a fair hearing. 

No mistake Mueller is acting as a judge in this it will be his decision as to what the outcome will be and if he is indeed as honest and professional as you deem him to be then he would resign without being asked. This isn't anyone attacking him I was all for him based on his reputation, but now that the facts of his long standing friendship and close working relationship with Comey have come out I see it as a conflict of interest cut and dried, friends do not investigate friends.