Rowan Williams is trying to hold the Anglican Communion together. This is a central mission for Christians if we take John 17:21 seriously, that all may be one. But this does not mean that it will always be successful or that any route works. It has to begin with a few starting points. There needs to be a dialogue, and this dialogue has to be built on the supposition that the other has something to inform us of God and God's workings in the world.
And because the other has something which can inform us, we are ready and able to have our views mutually transformed in the encounter. But if either sides thinks of the other as non Christian, totally separate from God, then there's no reason to talk. The only routes become conquering the other side or splitting. Since the first option is not possible in the Church of England and the Anglican Communion, the latter option seems to be the likely route.
There are of course half measures and piece meal compromises. William's recent decision to not be at the consecration of women bishops is such a measure. But like any such measure it is rightly met with scorn on both sides of the fence. Allowing gay clergy to marry but require celibacy is another such measure. Instead of support, Williams receives threats of schism from Akinola in Nigeria and bewilderment by liberals at home.
Until there's mutual dialogue and a desire to see what God is up to in the other, William's half measures, will do nothing to slow down, may even hasten the breakup of the communion. Some rejoice in that. But if the church can't demonstrate what loving community and the spirit of reconciliation looks like to the wider world, I have hard time thinking that we are in a position to present Christian faith as some model or resource in our world today.