From a strictly utilitarian standpoint, it’s a good outcome. I’m not so sure about the legal reasoning.
In a perfect criminal justice system, I wouldn’t lose much sleep over a repeat child rapist being put to death, any more than I’d lose sleep over a repeat killer getting the same punishment. If it’s not consider cruel or unusual to execute people for heinous murders, I’m not sure why it would be for heinous sex crimes against children.
But in practical terms, the decision is a good one for the same reason any limitation on the death penalty right now is generally a good idea: We’re miles away from a perfect criminal justice system.
From my own experience, I’ve seen far too many cases involving Dr. Hayne alone where he has found evidence of rape or sexual assault where other, more reputable doctors didn’t–and the defendant was convicted, anyway.
And let’s not forget, we have a troubling history in this country of convicting people of child sex abuse charges that later turned out to be false.