Glen, I agree with your legal analysis.
I think that the bigger picture is more important. Freemasonry isn't church. It does not specify any one volume of the sacred law, and certainly then can't go on to give an authoritative reading of certain passages in it. There are very few Christian only Grand Lodges, and I think that it is better to treat them as an historical anomaly, simply on the grounds that when most Freemasonry dropped Christianity 200 or so years ago, they maintained it as a condition of membership, and there hasn't been any change since. Their's was the original position, and it is the rest of us that have changed. It could be argued that it is them tolerating our change to become more inclusive, rather than the other way round. I think you make the point well though that this would only be an issue if Grand Lodges started to try to going back to being exclusively Christian. Perhaps that is the actual crux of the problem. For 200 years we have been based on Enlightenment ideals of toleration and equality; we haven't had definitions of morality. It's not original to me but there is a very, very strong case to be made that the moral content of Freemasonry is based on Aristotelian virtue ethics, rather than normative prescriptions. If you read the Nichomachean Ethics, you will find that Aristotle give the example of the virtue of courage, being the midpoint between rashness and cowardice, which we act out in our Lodges. You will also see that if you are in the virtuous position between two extremes of vice, but for all the hundreds of different virtues, you will be standing at the centre of a circle. This is very explicitly stated by Aristotle. So I tested this by going and looking through obscure manuscripts in the UGLE library, and there is one 18th century manuscript that has an alternative opening for lodges, which includes the phrase "Brother Aristotle". The morality of Freemasonry isn't prescriptive because virtue ethics isn't prescriptive. Both try to shape a person's character over their lifetime. What we have in Georgia is an attempt to impose prescriptive moral laws on Freemasonry, and in a sense, the (ex?) Grand Master is trying to reimpose Christianity by the backdoor on an organisation that gave it up as definitive 200 years ago. The Enlightenment ideal of toleration was a response to the terrible wars of religion in the previous century and it is with good reason that discussion of religion is banned in our lodges. By picking one interpretation of one sacred volume and trying to impose that across a whole Grand Lodge, religious disputes have been reintroduced and I think it is pretty safe to say that harmony between Freemasons and lodges, and masonic neighbouring jurisdictions, has been seriously upset in Georgia. This affects all of us because now our enemies can say there is a Grand Lodge that excludes gay people (and although technically amended to include fornicators, I would be astounded if the number of disciplinary actions was proportionate between gay and straight relative to their numbers). This is a terrible retrograde step; it plays into the hands of our enemies; it is probably a foolish reaction to the Supreme Court's equal marriage ruling; it creates major disharmony between brothers, and between jurisdictions; and it sets us back in the eyes of the public years if not decades.