Maguire seems a capable and honest man, but he's just started a new job, working for a criminal organization, and he is in way over his head.
He had trouble reconciling his loyalties to employer and duty to country. I sympathize with him. I've been there myself.

I wonder if the DNI he replaced left working for the Trump White House because he couldn't reconcile those loyalties either. Maguire reminds me of a stock fictional character; the idealistic and honest rookie cop assigned to a thoroughly corrupt precinct. He's realistic enough to realize that sometimes you have to bend the rules just a little in order to get the job done, but he had no way of anticipating that in his first few weeks on the job he's been expected to cover for his superiors, and that the Police Commissioner was on the take.

A parallel observation: Isn't Nunes a slimeball?