We're a nation of fighters, we never give up!
He's not retiring. He is going back to prosecuting.
I think he is acting too. What he actually said was that if the intel agencies had a reason to believe that there was foreign meddling inside a campaign, of course they would put informants in the campaign. And that is true, its just that "evidence" they had about that happening was a made up dossier paid for by another campaign.
"Stepping into a new role" I don't know enough about the flow of the judicial system to even guess where it would be that he would go.