This is the most legally sound argument against it.
Sure it’s bad to diddle kids, but it’s even worse to not have diddled kids, be accused and falsely convicted, have you genitals removed, and then on appeals the court is like “yeah sry bro they fucked that up, just reverse it”.
Although a lot of people think the death penalty is bad for financial or logistical reasons, but in my opinion the biggest reason against it is that there’s no quick way to revive a person when a court later on says they got it wrong.