At the core, the matter of LGBT "rights" is secondary to the issue of forcing a business to make something they don't want to make.
It could be a customer demanding some business make left-handed, chrome-plated, multi-colored widgets when the company does not want to make them.
The only actual case of discrimination arises when a customer is refused THE SAME service provided to other customers. Demanding a special service is not the same thing as being denied service.