User blog comment:Willbachbakal/Singleplayer Plasmids: Hypnotize/@comment-4165353-20110810125123/@comment-1330314-20110810134358

I think that may have been added as a balance measure, since otherwise you'd just be able to befriend him again. What I recommend you do is try and get your Big Daddy to soak up as much damage while he's under your control, and then finish him off when you think he's about to turn hostile.