Of course no JW elder would agree to perform the ceremony, nor would they allow the Kingdom Hall to be used for the ceremony. Isn't that discrimination? What would the legal consequences be if the JWs refused to sanction the union?
That's basically the slippery-slope argument evangelicals of all stripes have been making in response to the ruling.
In short, the law does not currently require that churches marry gay people no more than it requires that a Catholic Church marry a pair of Muslims.
But what about that bakery that was forced to bake a cake for a gay wedding? If you can force a bakery to bake a cake can't you extend that logic to churches and force pastors to marry gays? Can the government revoke a church's tax-exemption in order to force them to marry gays?
Well, in a word, "no." At least not yet.
Seems to me that the underlying paranoia is less about this particular court ruling than it is about secularization trends. It's not difficult to imagine a world where society would no more tolerate a church refusing to marry gays than it would it refusing to marry black people. We don't live in that world and it's possible we never will. Evangelicals do not have full confidence that they'll be able to stem the tide of public opinion, though.