@Bijou, I don't know how any hair unrelated to armpit hair entered the discussion, however it isn't a double standard. I'll explain why with one question.
Do you have a personal opinion about men wearing facial hair?
You don't have to shave your face, but you likely have an aesthetic preference one way or the other. You are entitled to that preference.
Armpit hair is exactly the same thing. It is about aesthetic preferences which people are entitled to.