I think it's legit taking things into consideration and Rahm is a big part of that. This is his first hard job being in the public eye whilst being responsible for a LOT of other people on his team. It's showing with his mismanagement of his personnel choices being fukkups. He's convincingly survived every single one so far but this one is very big.
Rahm is also a seasoned vet. He won't hesitate to throw his colleagues under the bus (Rauner, McCarthy, etc) if it means keeping his political status (Chicago Mayor is nearly a lifetime guarantee which is why he went for that job) because if you play the game you gotta play it right with Rahm. He knows the give and take game better than anyone else in the state. They call him Rahmbo for a reason. He got around the Park District for tourist attractions. He gave no help to Riot Fest. Rahm is the hand that feeds.
Personally I think he's gonna let the DoJ fukk the CPD as much as he can let them. McCarthy already is taking the fall and I'd be surprised if he didn't get some severance there. Whatever Rahm conjures up now is gonna hit the people good. They won't forget this so easily and lucky him, four more years until another mayoral reelection so he has time to iron this shyt out so when the time comes he's not seen as a resigning enabler of this nonsense but the man who fought and got the corruption out. All about how you paint the picture.
Sidenote, teacher's Union is
right now with Rahm's image taking a plunge.