Well, I hardly see these guys exorcising their right to take it to court as some heinous act. It is likely a waste of their time and money as I doubt the UK is going to "force" a church of any kind to perform a ceremony they have stated they won't perform. In the United States that is in direct conflict of the separation of church and state and seems as likely as repealing the 2nd amendment.

Marriage here is a legal construct where the couple is recognized by the government and granted certain benefits and rights due to that recognition.

Marriage and religious organizations are a totally different matter and unless we decide to throw the whole separation between church and state out the window and the government and the church merge into some insane and unholy entity...which seems as likely as the NRA and PETA merging to launch a full bore campaign to stop eating meat and repeal the 2nd amendment...I think we are pretty safe in assuming that people can make all kinds of noise about what churches do but it remains a voluntary issue whether or not one desires to join a church and so if you don't dig that your local House of the Nailed Up Nazarene won't perform your ceremony you have a right as an American to go elsewhere.