I met a lot of folks like that in the 20 years I was a Police Officer. If your too thin skinned you won't be a cop long anyway. If I were still in the business, I would treat him just like I would anyone else, and I would answer a call for help just like I would for anyone else.
If you let personal feelings get in the way of your job, you shouldn't be wearin the badge. I could never bring myself to eat in an establishment that was owned by a cop hater anyway. Ya can't tell the difference in a licked spoon or a washed one. They look the same.
When I ordered to go pizzas I would use a fictitious name, as a lot of teenagers worked in the pizza joints, and I was well know for my K-9 work, and SWAT work. That was before caller I.D. and pizzas are like those spoons I mentioned.
I've also had those same cop haters cry like a baby when an officer caught'em dead to rights on a traffic violation or crime. Ya just smile, and keep writing.