Because he isn't. Which is why he did what he did.
Laid out the case clearly, concisely and with zero possibility of what he said being spun or misinterpreted. Then flat out told everyone - in public - that there would be no prosecution.
He's throwing the case to the only court still available to him - the court of public opinion.
While that is plausible, I think what may be closer to the truth is that he laid out the entire criminal case that the FBI staff uncovered at that conference, so that the agency wouldn't have a mutiny on their hands and find half the investigative staff walk in protest.
That none of them did walk matches what we have seen of the military brass that also stayed on while their entire apparatus is being dismantled and made a joke.
This is what a post-coup looks like folks.
No one willing to rock the boat because they fear what will happen to them if they do.