I am frustrated that such brilliant men with such a long brilliant intellectual and spiritual history can get this so wrong. This judgement in this matter is flawed in two ways, and would make a great thread of its own.
Both men experienced WWII, and its various genocides, in ways that no American (with the possible exception of certain refugee/immigrants) did, and that experience coloured their views on capital punishment. They have a positive horror of it that we can't really get access to. For them, it looks like National Socialism or International Communism, employed by the very worst of criminals. For us, it's how we get rid of the very worst of criminals.