I think it's stupid. It is better for such people to apply the death penalty with prolonged torture, so that they suffer during life. After death, they do not care what happens to their body.
Then insane people like you will think thermonuclear weapons are acceptable, then life on Earth will cease to exist.
Sounds evil but I believe even the most callous criminal would not want to spend all their remaining years like that. It would be a fate worse than death that they wanted.
Do you offer to spend billions of taxpayers' funds to satisfy your sadistic desire to see how they suffer? If so, you won't receive even 1 cent from me!
P.S. Death penalty must be as cheap as possible! We need good healthcare, roads, education and not prisons!