When you are convicted of a serious pedophilia related crime with irrefutable evidence against you or a confession, the min. sentence should just be execution. The likelihood of re-offending is so high and they have already done monumental damage that it's much better from a Utility point of view to just put that person down.

Sexuality is something you can't re-wire. You don't get to choose your sexual desires and compulsions. You can't "pray the gay away." Some people are asexual and they are attracted to nobody (or thing, if that's what you fancy. No judgements). Similarly, you can't stop a pedophile from being a pedophile. The only difference with pedophiles is that they are wired to cause serious negative Utility, so the negative Utility brought by killing the pedophile will be less than the negative Utility the pedophile brings if they are left alive to continue to commit atrocities.