So that it may be discuss, why else?
In all of its usage this is the case.
Explain your reasoning; it seems to me that you believe, Susanoō, the literally physical manifestation of chakra, cannot be sealed by the Totsuka no Tsurugi since it survived a bijūdama and for it being unable to pierce Sasuke’s Susanoō for some unlisted reason; even if Sasuke’s Susanoō was layered in Enton by Kagutsuchi the Totsuka no Tsurugi can still seal it—the only way or ways that the blade cannot seal Sasuke’s Susanoō is either it undergoing some metamorphosis that changes it properties or Itachi dies—or some other particularity.
I am not hungry right not, Waltz may be—Drae' seems to be enjoying an appetizer though.