Board Thread:Online Discussion/@comment-9601450-20130602013609/@comment-3076045-20131019011641

Morag Tong would only be joinable if playing as Ebonheart Pact, if you think about it.

Although, I imagine it should at least be possible to have quests from them, or something similar. (They did, after all, create the Interregnum, the period of time in which this game takes place).