Why shouldn’t they? I mean, to be fair the Christian businesses we are talking about weren’t hanging up “No Gays Allowed!” signs. Anyone could come into the stores and buy any product that is nominally for sale. What they restricted was specialty items, such as wedding cakes. Certain bakeries didn’t make cakes for same sex weddings, just wasn’t a product they offered. I think they were well within their rights to do so as well, it’s their business, their labor, their cake. And here would be the same, the fundamental isn’t shifting. Labor and property rights form the foundation and those are innate rights to all humans, even Muslims.