The guy wasn't unusually rude or anything. He even said he was grateful for Andy's attention given the murders that have to be investigated. It is more that Andy disapproved of the existence of gays at this early stage, and his time being wasted on a crime only made possible by gay interactions, when he wanted to investigate the homicides.
I think it's a bit harsh to say he *hated* gay folks. I think it was more he was incredibly uncomfortable with the idea. But look how he interacts with the girls he likes, he's uncomfortable there too. I think sex stuff was probably the only thing Andy was bashful about or whatever when feelings were real. And some dudes are just that way. I'm not gay, I'm bi, but I never got the feeling he hated gays. I can understand being super uncomfortable though. It wasn't something everyone was conditioned to be used to back then. And I sure disagree with how politics tried to make me "accepted". Especially since I never asked for that. If anything, I feel more shame in how politics treated everyone else, than I am about not being 100% straight.