He shoots her an annoyed look. "I'm not willing to do it. Because doctors. Scare the shit out of me." And... yeah, okay, because he knows he'd be useless without it. But probably 60% because he couldn't let a doctor near him without a complete meltdown and possibly (probably) hurting said doctor. "How do you think I got this arm and the serum. I was a science experiment, Lehrer."