The story Cody/Donut has given on multiple occasions is that he was a bit "squeamish" when it came to the truly fucked up shit cops see and deal with on a regular basis.
Part of this is due to him being a single father (the story of his first marriage/wife and how he managed to get fucking custody of the kid in a world where the court system RARELY gives the dad sole custody is a story he refuses to talk about to this day) and the fact that he was filled with a lot of fear towards leaving his son with no parent, since (while he was in the military) he had his parents essentially raising the grandkid until he got discharged and took over as primary parent.
Shit came to a head when he had a freak out at a particularly nasty car crash after the Buzzfeed article that introduced him to the internet happened, where a bunch of people were horrifically mangled/killed in said crash. By his own word, a supervisor was on the scene and saw Donut barely holding himself together at the sight of the dead bodies while everyone else was stonefaced and unemotional and afterwards, pulled him aside and told him "cops have to remove emotion from the equation when they deal with horrors like this and you clearly can't do that. I would strongly suggest you find a new line of work, because you clearly can't compartmentalize the way cops need to compartmentalize to do the job".