His Will Be Done. Is Mr. Tutu alleging that, were God to be "homophobic", there would be a moral judgement beyond God's? Doesn't that void the entire concept we have of the Christian God? And with Hell being defined as total and utter separation from God--thus resulting in all sorts of awfulness without His presence--Tutu would be dooming himself quite much to opt out of heaven.
A homophobic God would void the entire concept progressive Christians have of Him, yes. I don't know if I'd say Reverend Tutu is arguing that there is a moral judgment beyond God, but rather that if God's kingdom is a homophobic place and homophobia is one of the moral judgments, then he'd want no part in it. In other words, all his advocacy of equal rights would have been for naught. And personally, I can't blame him for feeling that way. If you found out that God thought killing kittens and kicking babies was the right thing to do, what would your reaction be to that?