Rosenstein was smiling as he went to see Nunes. Grassley was smart to send that letter to Rosenstein asking for prosecution of Steele. Grassley is effectively saying: give us the scalp of Steele, admit you f’d up and we’ll let you go. Maybe.
I think Grassly is playing a deeper game. He knows Steele is not the guilty party here. He knows the FBI lied and set up this house of cards. He is asking them to investigate Steele knowing that they will dig a deeper hole to fall into if they do not come clean.
Letting Deep State Rosenstein go in order to get outsider Steele wouldn't be a good deal.