Broadly speaking, the situation you described is legal in the US. We have protected classes that you're not allowed to discriminate against, but "political belief/affiliation" isn't one of them.
Actually, it’s not in Sweden either. I thought it was, but it’s apparently not.
There are other laws that prevent business owners from denying people entry or removing somebody from their store or similar (see Supreme Court decision NJA 1995 s. 84). They can’t even prevent people who have historically stolen from them from coming in and spending time in the store. But apparently they don’t have to do business with them. I thought they did.
