People eat lunch every day. Regular meals are a basic human need. Wedding parties, however, usually only occur once in a lifetime. I think it’s extremely problematic to put them in the same category when it comes to discrimination law.
I can see why a hungry homosexual would want a sandwich from a homophobe. But see no reason why a homosexual couple would want a homophobe to serve a hundred sandwiches at their wedding party. If I knew a caterer disapproved of my wedding, I wouldn’t even let him serve me if he wanted to, let alone force him to. Such a request is not a dignified one, and accordingly doesn’t deserve to be treated with dignity.