This quest was marked obsolete by Blizzard and cannot be obtained or completed.
Learn the purpose of the Stone Watcher of Norgannon, and then interact with the Uldum Pedestal in the Tanaris desert.
Learn the purpose of the Stone Watcher of Norgannon
"Salutations - I am a guardian of entry. Unless you have the Plates of Uldum already integrated with your disc set, I will not allow for entry into the Uldum compound."
The appearance of the Stone Watcher of Norgannon must be the reaction that was hoped for in sending you out to the Tanaris desert with the platinum discs. As instructed, you will need to find out what the story behind the Stone Watcher is before continuing on.