As I said, there is a zero percent chance of that happening. Death penalty spending is hardly the obstacle to ending poverty, providing health care, investing in infrastructure, or anything else.
And he’ll hardly be rotting. He’ll be getting food, shelter, and healthcare. I’m not saying prison is fun, but they are not just throwing away the key.
As someone who has moral principles, I would rather the process by which he can be executed by the state not exist, because any law that the state can use to rightfully kill a guilty person can be abused to wrongfully kill an innocent. The state can never be truly 100% certain of the defendant's guilt, and so there can never be a 100% guarantee that only guilty people are executed.
That's exactly what they said about Cameron Todd Willingham. Professional firefighters took to the stand and said that there was no way his house could have burned the way it did without accelerant. They were as certain of his guilt as you are of this guy's. It turns out even "100%, no doubt" isn't a high enough bar.
The next person could be. As I said, any law that can be used to rightfully execute a guilty person can be abused to wrongfully execute an innocent. Not every person on death row is as certain as this case, and as much as you will say "it should only be used when there's this much proof," in the real world, it won't be. Better to be rid of that system altogether. We don't gain anything from killing someone.