Shiba never expected that his master would ask something like that because that was exactly what he wanted.
Saving the timeline in which he lived was meaningless for him, and he didn't think he was worthy of living a happy life after having failed to protect Eini.
Thus, it was perfectly fine for him that the Shiba that would experience that timeline wouldn't be him. He would gladly let his own past self have a different future even if he needed to stop existing in exchange.
"That is exactly what I wish, master. Tell me, what should I do?"
Life seemed to have come back to Shiba's eyes.
That was the timeless border, so the bodies there were created by their consciousness, which easily showed the changes in their mental states.
"As expected of my best and last disciple. You lived up to my expectations."
Liye hadn't accepted any new disciple after reincarnation, and no one of his disciples had even been stronger than Shiba, so Liye wasn't flattering Shiba.