Well, that was my understanding, anyway. I could be wrong or things might have shifted since it was last discussed.
What, like that time her lookalike passed Amelia in... I think it was that port city in the first ep 17, with the slashdragon?
Xel actually does understand that this isn't the Zel he knows, and he did try to make nice at one point, but they had a conflict where he was prepared to tell Zel some things that were classified as need-to-know, and Zel was unwilling to talk to him without lots and lots of chaperonage (people who did not need to know and who Xel could therefore not have around), so it never actually made it into the comm. Xel's feelings and pride were deeply, deeply hurt by things that happened and things he found out while trying to make arrangements for this, and now he is absolutely not going to try and make any first moves towards Zel again. I wouldn't have a problem with trying to fix things at all, but pretending that didn't happen just because it didn't make it into a thread wouldn't fly with Xel. It affected him too much.