If you read my earlier post here, it might offer some insight:
So if you took your 80 there and even just interacted (or attempted to interact) with Rohl Tahl, you are now locked out of being able to do ToF on that character. Its frustrating and annoying and needs to be changed, but until or unless Blizzard does make ToF available to people, the campaign is sadly the only way you can get to the Maw and beyond on that toon.