They absolutely could do that. You and I may not like that, but they should absolutely have the discretion to do that, when they’re negotiating individual terms with individual clients.

No, they can’t. They cannot simply because they are a protected class. If there other reasons, they can.

If the photographer was a black woman who’d been sexually assaulted by a white male police officer, should she be legally compelled to provide her services to a retirement party for a white male police chief, regardless of whether or causes her significant trauma?

Not because he is white. But yes because he is a police chief, or just about any other reason.

What if instead it’s someone who was raised Catholic then eventually left the church with some hard feelings when they married an atheist…and now they’re being asked by the church to cover a fundraiser event the church is putting on? Or even just a Catholic family having a confirmation or something and they want the photographer to document the occasion?

She could decline because its a church, a business, but not because a client has a religion.

… my point is that it doesn’t matter what I think, and that a freelancer should always have the right to not enter into a contract for any reason. Sure, that freedom could be used in ways that allow them to express their bigotry, but I feel that’s a possibility which is an acceptable cost/risk in return for the freedom of these freelancers to choose how to do business.

The rest of the paragraph is what you think. It is not what the majority think, and that is why laws exist as they do, because the majority voted for them.

Just my opinion and you’re free to disagree!

I do disagree, and so does the law, excluding OPs post and thus why this is relevant and important to understand. You’re still trying to frame this as a business model, but it’s about protected classes.