My theory on Session:
He recused himself, since that was required by law and by legal practice ethics. Many fault him for recusal, out of ignorance.
He seems to be in over his head; The Peter Principle appears to be demonstrated. Nice man, good Senator.
He is merely serving out his time. Firing him too soon would look bad.
So he plods on, taking up some causes. Often appears to be sedated or sleepwalking.