No your analogies are apples to oranges.
Answer my question. Is refusal to do a pornographic shoot discriminatory? Be consistent. Your position is that if someone wants a business to provide a service within it's type of services, then that business must perform it if they serve the general public. The wishes of the customer are paramount.
Now to your question.
And I answer for myself. I think such a photographer is bigoted. I think their conviction is wrong. That it is unsound. And that they should/ought to do a photo shoot for such a wedding. But, that the couple hiring them would be better served choosing another photographer.
But should it be illegal for the photographer to refuse service? Probably not (though I realize that's not a popular or appealing position). We want everything to be black/white (pardon the pun) and we act as if there is some sort of common, agreed-upon, moral code to which we can appeal - but there isn't. What we do in the end is encode one morality over another - one person's freedom over another's. It's all about power.
Thinking further though about your scenario, I wonder, would a person that believes interracial marriage is wrong, be willing to do a non-wedding photo shoot of the interracial couple? I doubt it.
I know the baker in CO was willing to provide his services to that couple for other things beyond the wedding cake.
Now to your concluding opinion, I think that's the only option now available for photographers and bakers and anyone offering wedding services. But, it will challenged and it won't stand either.
Because, again, it is all about approval…and submission...