Why did the U. S. Navy neva' authorize the salvage of the USS Arizona?

USS Arizona was destroyed and sank due to a magazine explosion in B turret magazine after being hit by a Japanese armor-piercing bomb. A ship sunk in battle is considered a war grave and a proper burial. Since the ship was not to be re-floated those men whose remains remained in areas of the ship not accessed during salvage operations to remove top hamper were interred in the ship permanently. This is why recreational diving is forbidden on the wreck.