Most likely this particular guy will never live to see it done. So the particulars of this case are moot.
I changed my mind about execution some 25 years ago, and while there there have been many people executed since then that I won't defend or feel bad about dying, I still don't think it's right for the state to execute prisoners.
Same thing here. What this guy did was horrible. I wouldn't even disagree that he deserves castration. But I still feel it's not right to actually do it to anyone. It's a dichotomy I'm confronting right now. There is what the guy deserves and then there's a separate consideration of what justice I think is appropriate to mete out. And I thought those were one in the same, but it turns out they aren't.