But if I don't like poofs, why should I be forced to allow them onto my private property?
Remember - at one time, hating and discriminating against black people (as an example) WAS socially acceptable behaviour.
Remember that I said "assuming he isn't breaking any laws"?
This man is legally allowed out in public, naked but for a Winchester Pump. So it boils down to discriminating against him for his lifestyle choice.
What, in particular, is threatening about him anyway? Many people carry guns and somehow find the time not to kill people. Naturists are the least threatening group of people on Earth - "Gimme all the cash in the till" isn't usually well-accompanied by a lazy lob-on. 0.81mg/l is enough to stop you from driving, based on safety principles but again, many people manage to exceed this level without even once committing murder.
It seems that it is "right" to discriminate against someone who seems a bit weird, but "wrong" to discriminate against someone whose personal choices (whether or not homosexuality is a choice is another debate entirely, but most people who hate homosexuals seem to think it is) you find abhorrent - even on your own premises.
So you have two people - one odd, one gay - in your shop, neither of whom is breaking the law. You can refuse to serve one through personal prejudice, but the law (or "socially acceptable behaviour") says you mustn't refuse to serve the other through personal prejudice. That would be an inconsistent law.