They are required to attend. Which is quite enough to establish participation. The photographer who must attend may also make sure that everyone is told that the happy couple is damned for eternity and will burn in hell. But at least the pictures will be taken.Odd that the vendors are assumed to 'participate' in the wedding. The money they earn is from baking, delivering and setting up a wedding cake. Photographers are hired to document the event, but they are not required to wrap up a toaster oven in silver paper for the happy couple.When a baker must bake that wedding cake, a photographer forced to attend a gay wedding, they are forced to participate.
Gay rights are here to stay, the same way they were here to stay in Mesopotamia, Greece, Egypt and Rome. Gay rights stayed until they didn't stay any more.
A same sex wedding is an ideal place to proselytize. It's a convention of sinners ready to hear the Word.