Tobirama Senju was a clever man. He had designed Konoha's entire framework, so he understood Uchiha Yi's intentions. He saw no problem with them, either. The Hokage should not be shut inside the Hokage Office, bound by endless duties.
The Hokage should be the strongest person, someone who protected everyone, not a tool for processing paperwork.
Clearly, Tobirama was fairly satisfied with some of Hiruzen Sarutobi's policies. But he was deeply unhappy that those duties had kept Hiruzen tied to Konoha.
Uchiha Yi's approach would free him from a great deal of administrative work.
It would also give him time for other things. Konoha might not unite the entire Shinobi World, but a great many matters would still come its way.
As Konoha's Hokage, he would face a multiplying workload. If he continued to govern the village, and even the country, by the old procedures, then even someone with Uchiha Yi's Ōtsutsuki-like constitution might work himself to death.
In fact, Tobirama's concerns were entirely justified.
Take Naruto Uzumaki in the future. He had become the strongest person in the Shinobi World, fully awakened the Asura Chakra within him, and possessed a true Sage Body. Yet after becoming Hokage, the sheer volume of work left him without even the energy to create a Shadow Clone.
Uchiha Yi could create plenty of Shadow Clones to handle his work, but even he had limits. If he worked himself into the ground, it would be bad for the entire Shinobi World.
Hiruzen did not want Uchiha Yi to rush ahead. But when he saw that his teacher, Tobirama Senju, supported Uchiha Yi, he chose to remain silent.
Hiruzen would never doubt Tobirama's abilities. Even now, he occasionally found himself thinking, Oh, so that's why Teacher Tobirama designed it that way. Hiruzen would sooner doubt