That's the argument put forth by Robin Wilson in the LA Times, who says we need a "careful crafting of robust religious protections" in order to "legalize gay marriage without infringing on religious liberty."
In a stance reminiscent of those who would allow pharmacists to refuse to dispense birth control, Wilson maintains that not only clergymen and state employees but also "wedding advisors, photographers, bakers, caterers and other service providers" deserve exemption from involvement in same-sex weddings. They need explicit exemption, she says, because otherwise anti-discrimination laws may penalize them if they refuse — she cites county recorders in Iowa, who have been threatened with dismissal if they fail to issue licenses to gay couples, and a husband-and-wife team of wedding photographs in New Mexico who were fined $6000 for failing to photograph a gay ceremony.
Wilson writes that we should protect those who object to same-sex marriage from having to choose "between conscience and livelihood." She says,
Conscience protections are a thoroughly American idea. Since Colonial times, legislatures have exempted religious minorities from laws inconsistent with their faith. Such exemptions allow Americans with radically different views on moral questions to live in peace and equality in the same society.
However, America has also deemed certain "views on moral questions" unacceptable. Though some once considered interracial marriages immoral — and some still do — county recorders can't refuse to license them. The question is whether fostering a diversity of viewpoints on gay marriage is worth allowing people to discriminate against gays. And since people can choose their jobs, but not their sexual orientations, it seems more reasonable to ask "wedding advisors, photographers, bakers, caterers and other service providers" — and not gays — to yield.
The flip-side of same-sex marriage [LA Times]