Experimenting at the request of inmates, prosecutors or judges invites cynical abuses prohibited by strict ethical guidelines. Giving mentally disordered offenders like Thiel false hope that castration is his ticket out of prison sends the wrong message. There's nothing wrong with that. But there is something wrong with attorneys, judges and hospital staff buying Thiel's argument that castration entitles him to an early release. Castration won't counteract his mental illness or criminal propensities by simply reducing testosterone.
Criminality involves more than imbalanced hormones or faulty genetics.
Believing otherwise invites dangerous naivete leading to unwarranted medical experimentation. It's OK to neuter or spay dogs for whatever reason. But it's not OK to castrate mentally disordered sex offenders because they wish to voluntarily commute their sentences. While it's logical that lowering testosterone weakens sex drive, it's also true that raging hormones aren't responsible for criminal activity. Before castration mania gets out of hand, scientists need to carefully study its effect on aberrant sexuality and criminality.