That Fractal shit that's going on is the perfect excuse. No Mists ghosts, no echos, no memories, just a straight alternate-reality-version of the Mentor, flesh and blood and all, from a timeline where Claw Island didn't end with death and sadness.
I don't care, I just want to have a conversation with Sieran again.
Give us a version of our Mentor from a timeline where Claw Island DID end with death and sadness -- but it was the commander instead? Mentor and student reunited after all this time.
A chance for both to have the other back, and do better by each other next time.