I think a lot of this is pretty basic, but it seems that some are overly fixated on the homosexual aspect of this so I'll write it anyway.
It isn't about sexual orientation, it is about prurience.
Probably. It's really stupid the way we hide disguise our bodies, only to turn around and flaunt them for sexual gratification and then get insulted because someone finds us attractive.
I won't argue that there are drawbacks to some of the sexual hangups our culture has, but that is not the same thing as pretending that our society doesn't have them, or deciding to unilaterally ignore them. One of those common hangups is a fear of being undressed in front of people who receive sexual gratification from that exposure without our approval. It is this hangup that makes me think that our society isn't quite ready for unisex changing rooms and coed bathing facilities, and until it is normal to have mixed changing rooms, there will be some level of concern about homosexuals using the same facilities and for the same reasons.
The primary cause of conflict here is the dislike of someone taking prurient interest in nakedness outside of a relationship that expects or encourages sexual stimulation. Outside of those specific relationships - which may be monogamous, polygamous, commercial, or what-have-you - it becomes creepy, rude, and discomfiting.
It only becomes insulting when the intrested party can't take "no" for an answer.
I don't know if that is true. For instance, a random creepy guy might accept your "no" when they suggest a sexual activity, but continue to ogle you from across the room to the point of making you uncomfortable. A parent might pass around a picture of their toddler in the bathtub to normal folks who receive no sexual gratification from such a photo, but if someone began to get aroused and breathe heavily when they saw the same picture, the parent would very likely be upset. Likewise, we think little of nudity for medical, artistic, scientific or other non-sexual purposes, but if a gynecologist were to start playing pocket pool during an examination, most patients would be understandably alarmed. When someone's "private" naked photographs are stolen or shared with people outside their target audience, most of the time those people feel violated and used.
It's not only a problem when an interested party refuses to hear your "no".
And maybe that's what Culliver is scared of. That he wouldn't say "no". In truth, THAT'S what homophobia is a pathicalogical fear of. It's not that a person is scared of gays. It is the fear of being gay. And there is nothing more frighting then being scared of yourself and what you really want.
Do you really think so? I'm sure there are some real-life examples of people who were overtly anti-homosexual in a subconscious rejection of their own desires, but that is hardly the norm.
Don't get me wrong, I agree that there is a significant introspective component to it, just not in the way you propose.
We segregate changing facilities by gender not strictly so we are surrounded by people with similar plumbing, but because on average it protects us from having to be concerned about someone staring lasciviously at us when we are vulnerable and undressed. Are those concerns realistic? Maybe, maybe not; there are a lot of people who don't have to worry about inspiring lust in others. Even so, a young, straight person of either sex at some point probably daydreams about what it would be like to be a fly on the wall of the other changing room, and they aren't thinking about averting their eyes. My opinion is that Mr. Culliver is probably subconsciously reversing the roles by mentally placing himself in a woman's locker room. If he would want to stare lecherously at attractive women as they shower, why wouldn't he likewise be concerned about a homosexual man doing the same thing in the men's locker room?
If everyone kept their eyes to themselves in locker rooms, there would be little reason to split them up by gender in the first place. Realistically, people in our culture don't tend to do that. I don't think it is homophobic to believe that a homosexual might behave similarly to a heterosexual when surrounded by unclothed members of their preferred gender.
When I was in high school, I remember a group of kids sitting down at lunch talking about (what else?) breasts. One moderately attractive girl couldn't understand what the obsession was. "They're just fat and skin! They're no big deal!" When some of the guys at the table offered to inspect, touch and photograph her no-big-deals she immediately turned them down. Even if she truly believed that exposing the female chest wasn't a big deal, when it was a big deal for someone else it suddenly became one to her.