Like someone already said in here,
I would say that the type of people that are "terrified" are the type that are "hyper-competitive".
They're extremely status minded and constantly want to tear people down to pull themselves up.
It's also why they're disgusted with non-manliness, which is not the same as gay in my opinion.
You can have a manly man who is gay and a girly man who is heterosexual.
Even making fun of acting tough behavior gets them into disgust.
You can't have fun with these people.
I do have to say, before I was in a relationship,
I would get annoyed if mistaken for gay and thus prefer to avoid any confusion.
I consider the dating market to be skewed in favor of women simply by the numbers
and anything to further pull down those chances was the last thing I needed.