Yep, he exercised an incredible level of restraint. Far more than the law requires and probably more than he should have. It’s hard to fault a man for not killing another man though.
Paperwork, civil suits, internal affairs; small town, and he may have thought the guy wouldn’t really pull the trigger on him (history has shown that that was probably a false assumption if it is one that he made).
I do wonder if the guy had a history of being a mean snake, or if he was evidencing age related personality changes.