is bleach episode 58 filler?

With Ichigo Kurosaki having relayed the name and explanation of his Zanpakutō's special technique, Getsuga Tenshō, 6th Division Captain Byakuya Kuchiki comments on how pretentious it sounds and decides to give into Ichigo's demands that he use his Bankai before holding up and dropping his Zanpakutō. As Ichigo expresses surprise at him letting go of his sword, Byakuya stoically promises to turn Ichigo to dust before he has time to regret his decision while his Zanpakutō sinks into the ground as though it were water.