User blog comment:Xilinoc/Ch. 595 - Rubb-Dolls 2/@comment-24031741-20140905175001/@comment-5398287-20140905230635

More a case of the Idiot Ball. From what I can tell, Kubo had Byakuya discarding his Zanpakuto like that because Senbonzakura has become so tremendously OP that it can take out 3 Vollstandig-using Sternritter with ease, so him not having access to it was kinda necessary for the battle to last more than 3 pages.