What, in the civil rights act or the constitution, or in any state law, prevents me from saying “I refuse to do business with anyone whose name is Bob?”
Like i said, there are some specific protected classes - you can’t discriminate based on race, national origin, gender, age, medical condition, gender identity, etc. (depending on your jurisdiction there can be a couple dozen classes, or only a handful). But otherwise there is nothing stopping a business owner from declining to do business with anyone they want to.