Why Doesn't the Soul King Fight Back? Three Questions

The creation of the Three Realms had been the separation of spirit particles from material particles, of life from death, thus establishing a new cycle and a world where life and death were kept in order.

That had been the shared goal of the Five Great Noble Families.

Thus, the purest Soul Society had been established first, followed by the World of the Living, the world of material particles. Only then came Hueco Mundo, which housed Hollows...

And last came the "Dead Silence World," which even the Soul King's power had been unable to separate and assimilate... The Five Great Noble Families had cast it out of the Three Realms.

"That is Hell—the dumping ground for everything the Three Realms cannot assimilate!"

Aoto had also entered the bathhouse by then, listening to Tenjirō Kirinji's words...