I am not a liberal anymore than you are a conservative, Bern80.
Your common sense is not the basis for our law.
The Constitution, case law, and statues are basis.
You may associate privately, but if you are in business with a service or good for the public, you can't discriminate because sex, orientation, ethnicity, religion, race, and so forth.
This the law, and this is good law.
what do we call a business not run by the government in this country? Oh yeah! We call it a PRIVATE business. Secondly, you don't get to just make up definitions of terms. Public good has a definition. A definition not met by anything a private business sells. Public goods have characteristics such as a) consumption by one does not reduce supply for another, b) non-exlcudable, that is they are hard to keep non-payers from consuming, c) consumption is mandatory. A road, for example, is a public good.
Again freedom of association means the right of people to engage in whatever transaction they agree on. That is no different for a business. It just appears that way to you because that gets lost sight of when you have a lot of consumers going to a business to purchase an item. At the end of the day the transaction is exactly the same. A consumer and a seller come together and agree on terms of exchange. That is EXACTLY what freedom of association was meant to to apply to and you simply fail to see that if you don't have the right to not associate with someone, regardless of the reason, regardless of whether it's your business, you realy have no individual freedom.
Conversely your opinin of what freedom of association means makes no sense. You say it only applies to individuals and what they do in their personal life. Under that premise, what would a lack of freedom of association look like? Pretty ridiculous. If it was only meant to apply to people in their personal life and there was no freedom of association the government could by law require you to entertain a conversation with someone you didn't want to? Again, ridiculous, which is why it more likely that framers actually meant for that freedom to apply
primarily to private business.