I know that went the 1st amendment route, but I would think small business owners ought to have the same level of religious protection as Muslim cashiers who can’t be forced to handle alcohol in the checkout line.
More. The supermarket is a public accommodation. A bakery might be, but only for generic productions. This is something which hasn't been argued out. A baker should have to bake a generic cake, but shouldn't have to bake and decorate a cake to the buyer's taste which the baker finds obscene.
And, a photographer should be able to accept or decline commissions for any event (s)he finds distasteful.