Board Thread:Questions and answers/@comment-25177439-20170106025149/@comment-30711988-20170107094601

But him fusing with Noel didn't gave him Noel's powers, or else he would just deactivate the Master Unit and watch the unobserved world being erased.

And Izanami and Susano'o have similar objectives, just, Izanami wants to destroy one world, Susano'o wants to destroy more worlds, so he would be feared, which would make him stronger than Amaterasu, so he would be able to break free from her control. His goal, freedom, doesn't seem as bad as Izanami's "destroy the world just because".