User blog comment:Xilinoc/Ch. 591 - Marching Out the ZOMBIES 2/@comment-823339-20140730114655

Hitsugaya isn't dead. Kubo doesn't have the balls. If he can't kill Byakuya then killing Hitsu is impossible for him.

Not to mention Giselle's powers can work on Shinigamis without killing them, since she mentioned that only Quincies need to be killed before they can be zombified.