Frankly, I’d like to be able to consider that option. There are already transgenders who have themselves mutilated. There would appear to be armies of men in this country who just cannot control themselves, and voluntary surgery might be an option. Men are so hard-wired for mating with those younger than they are that maybe they should cut off the hand that offends them, or whatever offends them. Eunuchs are cheaper than incarceration.
Contrary to popular belief, castration does not reduce the sex drive of someone or even an animal after it has experienced sex over a period of time as the natural urge has already been cultivated.Cattle, dogs, sheep and hogs will still try to hump if they were not clipped at an early age. Castration of a human being does not mean the urge is not present nor will it neccesarily stop a sexual predator.
Transgender women take testosterone blockers and get bilateral orchiectomies because they feel that the testosterone is poisoning them and they don't care to use their male sexual organs as a man does, preferring instead to get the testes removed to look and feel more like a woman than a man.
I can tell you that even after being castrated it is still possible to fully function sexually as a man by taking shots of testosterone.
So if their mind is evil, castration won't stop them. If the intent is to punish the man and protect other girls from being victimized by him, then he still must be incarcerated to serve his time. Castration is not going to a sufficient deterrent or a sufficient punishment.
Prison is killing him? Well, I'll will bet the girl and the girl's parent's are not too happy either.
Penis amputation along with removing the testes would be the more definite surgical fix. Offer that to him...