"The Bishop IS the Church in his own diocese."
Sorry, I don't think so. They Church is the supernatural Bride of Christ, and does not inhere in any individual.
History shows us that there have been bad bishops, and even bad popes.
It is more accurate to state that the Bishop has absolute authority in his own Diocese unless Rome reverses his decision(s.)
That principle has been used for the good by Bp. Bruskewitz, who has told "some woman" on the Queer Commission to go fly a kite.
And Rome backs Bruskewitz.