If he is really sexually deviant and thinks this surgery will get rid of his problem, I think he would be incorrect. Criminal compulsions to act out and involve others in these events most likely originates in the brain, not in the gonads. Now if he was talking about the pros and cons of modern day lobotomy, well, he may be on the right tract. Messing with the brain though is also a huge gamble. Such a procedure, incorrectly researched, and located in the appropriate lobes may only serve to enchance, or exentuate his present compulsions.
Actually, there is very good evidence indeed that castration, chemical or surgical, is highly effective at reducing recidivism in sex offenders.
It is generally considered that child molesters have among the highest recidivism rates of all criminals, with estimates varying all over the place, from 25% to 50% to 94% (probably the result of a bad study).
Yet the various (limited in number) studies of those molesters castrated chemically or surgically show recidivism rates of 0% to 10%.
http://www.jaapl.org/content/33/1/16.full.pdf
This is no doubt at least partly because the group is self-selected from those offenders who apparently don’t WANT to have the obsessions and compulsions.
It is, IMO, entirely reasonable to believe that a person is not, or at least not entirely, capable of controlling his thoughts and particularly obsessive thoughts. That being more or less the definition of obsessive thoughts. A person may have obsessive sexual thoughts about children he finds repugnant at a concsious level yet be unable to resist compulsively acting on.
Such a person might indeed find considerable relief if castration reduces the hormone levels providing the driving force behind the compulsion. Or at least to my mind that’s a logical explanation of why castration might work to reduce recidivism so greatly.