TBH I’m having a really tough time with this one. I’m not a lawyer, but there are competing Constitutional interests here:

• the state government wants to protect its citizens from discrimination by businesses within the state, which is a power it has (limited by federal law and the Constitution)
  • Importantly, it is NOT a violation of the couple’s constitutional rights if the business refuses to serve them because they’re gay. That’s why the state law exists, because there’s nothing covering this at the federal level.
• But in this case, the service is also a form of expression/speech by the vendor, which (religious or not) is constitutionally protected.
  • If the business in question was a plumber, there’s no question the state law would apply; plumbing is not a constitutionally-protected activity.

So we have a state law compelling speech-based services from businesses in scenarios where the client is a member of a protected class as defined by the law. Who wins?

Keep in mind that the same decision also controls the hypothetical-but-plausible situation where the business owner is a person who supports LGBT rights, and who doesn’t want to design a website extolling the exclusive virtues of a Christian heterosexual lifestyle for some highly religious prospective clients.

Of course a buck is a buck, and some designers would take that job because they wanted the money. But should they be compelled to make that site? I wouldn’t think so, personally!

So that’s a tricky angle. There’s also the edge cases.

• Can a printing business refuse to print a poster design by someone else on their printers if they don’t like the message of the poster? Probably not, because the service doesn’t fit as easily into the speech/expression category
• What about a sign painter who doesn’t write the text itself, just stylizes it? Is the creative expression still linked to the message?