Given how flagrantly governments have been using pedophiles as an excuse for curtailing our right to privacy, I don't trust them to execute civilians for this reason (or any). False convictions (intentionally so, in worse-governed countries) are a thing, and I do not cheer for the prospect of giving the government yet another reason to murder its citizens.

Advocacy in favor of the death penalty is never about "death penalty for murderers/rapists" but "death penalty for people convicted of being murderers/rapists". Practice has shown there's a big difference