My guess to why Cipollone came clean, assuming he did.

[Novara]

5. I think a lot of people assume Cippolone is a bad guy ...

... because he worked in that administration. But his job as White House counsel was to advise on the legality and ethics ( ! ) of policy, decisions, and actions of the administration.

I have not seen any rumblings that in his official capacity, he tried to cover things up or weasel around legalities. Maybe he did that in some cases and I am not aware of it. But we do know that he was against the march of the mob to the Capitol on 1/6 and in his capacity as White House counsel was advising against leading the mob. That makes him a voice of reason. What else did he warn against?

And the inference I draw is that it likely isn't the only time he advised against some illegal, unethical, and/or flat-out criminal activity the orange motherfucker was about to take. And THAT makes his testimony potentially nuclear-level explosive. He is perhaps the one person in that administration who may have pushed back at illegality and criminal actions. And maybe got rebuffed along the way. In other words, he knows where the bodies are buried.

The orange motherfucker SHOULD be scared shitless.