Quote Originally Posted by ProstheticSoul View Post
You cannot make an expansion that inexorably follows the MSQ to its conclusion that is heavily centered on optional content that the player can miss.
As it was presented in 5.0, it was deliberately written so the story makes sense with or without completing the Crystal Tower storyline – making the assumption that if you have not completed it then in the other timeline that the Exarch comes from, those events happened and he experienced them even if you personally have not. Because of this, he knows you regardless of whether you know him.

The story carries more emotional weight if you know who he is, but the plot plays out the same either way.