User blog comment:Xilinoc/Ch. 590 - Marching Out the ZOMBIES/@comment-6657474-20140724020435

I find it somewhat amusing that Mayuri claimed he couldn't kill fellow Shimigami, even dead ones due to his "benevolent nature". He certainly had no qualms about planting bombs in the bodies of his own squad members without their knowledge when he first encountered Uryu and Orihime. I have a feeling he's just trying to troll Giselle, since he'd be the last person to have even a slight change of heart. Seems he's just gone to having others do the dirty work instead of doing it himself (sort of) like before.