I postulate that Priestap knows how exposed he is and that Comey tried to use him for cover and cut him loose. He's a savvy DC cat. He would seek out better protection than the IG could provide him. Only the DOJ can make him a reliable deal.
That's my theory.
Q lives
Well, then WHO at DOJ would give him that deal and in what context? Sessions is recused, Rosenstein is, in much the same position as Priestap and from all appearances compromised, and perhaps even fighting for the other side (we think). There is no named/announced criminal investigation ongoing at DOJ. So who gives him a deal and why does he take it? The DOJ is in some kind of limbo...maybe even warring with itself and the administration. What have they got to give him in all their dysfunction? And who would give it to him?
He can always claim that he vas just following orders. Hehehe.