This is about my position. If somebody wants to discriminate, then a business is not the right structure for them. Same with public service, if you choose to be mayor, your responsibility is to everyone, not just a preferred subset.
Edit: To go further, talking about where to draw the line. I think for a business that’s an easy answer, the law. As a photo business for example they’d have have the duty to be available for hire to photograph any legal activity. But someone asking to photograph abuse or something is crossing the line.