The Hitching Post Wedding Chapel appears to be a church and should be tax exempt and First Amendment protections.
They’re actually incorporated as a for-profit business, which is what opens the door to this sort of lawsuit.
Given the Hobby Lobby ruling, there’s no way this will survive a Supreme Court challenge. However getting there is going to be incredibly expensive for the chapel, and the plaintiffs are going to have very deep pockets to draw their funding from.
This is, pure and simple, Lawfare. Make this chapel’s owners defend themselves through multiple rulings and appeals, hopefully bankrupt them in the process. Setting an example for others.