Look, Rand Paul is a Libertarian. With the exception of one self proclaimed Libertarian, they don't believe government should tell private businesses how to run their companies and/or who to serve or who not to serve. They don't believe the government has any business telling a property owner what they can or cannot do with their own private property. There really is no surprise they hold those views. ANYONE who has a level of knowledge about Libertarians, should probably start with the assumption they believe things like the Civil Rights Act application to businesses and property rights was wrong.
Right now, I don't feel like going into the "what if" situations that I think puts some Libertarians in knots. But I will say this, for any Libertarian who has commented in the public square about the details of their beliefs and where it leads, if they are running for public office, it IS fair game to ask about those views, whether or not they are a part of the campaign.
All of the Rand Paul backers who are whining about "gotcha media questions," grow up. That's the nature of the game. Rand Paul wrote a public opinion article in the not distant past. It's fair game.