Uchiha Yi was not a heartless man. Quite the opposite: he cared deeply about the people close to him.
He could tell that Uchiha Mikoto and Kushina Uzumaki both cared for him and had feelings for him. He could not bear to give either one up, so he chose to pursue them both.
Given Mikoto's feelings, if Yi told her he had chosen Kushina, who was to say that gaining love only to lose it would not make her so furious she awakened the Mangekyō Sharingan?
Yi had been away from the village for nearly a year, but Kushina sent him letters from time to time, telling him what was happening there.
Though Yi was not in the village, little escaped his notice. Kushina was his main source of information, and she got her news from Mito Uzumaki.
Mito usually had little interest in such matters, but she had plenty of ways to learn about them.
Mitokado Homura still disliked Yi, and Shimura Danzō was even preparing to block his bid to become Hokage. Yi knew both men well. Once he took power, they would have no easy time of it. A new ruler brought new officials. Did they think they could keep their authority? Dream on.
Of course, Yi would not destroy them without good cause. That went even for Danzō.
As far as Yi knew, Danzō had not yet done anything to wrong him. If Yi persecuted him over a political struggle alone, how would he be any different?
But Yi knew Danzō well enough to expect trouble if he became Hokage. When that happened, he would have grounds to act.
Yi was strong enough to crush any opposition. He could even use Danzō stepping into his office with his right foot as an excuse. But that would