Simply put, even if they saw Sasuke and Naruto from the future standing side by side, they couldn't just naturally tie the two together and arbitrarily decide Sasuke's future while he was still confused.
He had to be willing, with a strong, driven will of his own.
Anyone who could conquer the other Herrscher personality within and master the full Authority had to be unbreakable in both body and will.
Chapter 144