The vast majority of people celebrating the death of the United Healthcare CEO would have been perfectly happy with him being stripped of power and imprisoned, but that wasn’t ever an option so the only thing available is death. There’s also some evidence that his death has actually made a difference, in the form of other health insurance companies chickening out of unethical policy changes.
In the case of these prisoners, they’re already safely behind bars. It’s also, broadly speaking, much more likely that they aren’t guilty of what they’ve been convicted of (although I don’t know anything about these particular cases). We also have evidence that the death penalty doesn’t have the effect on crime rates which proponents claim it does, so it’s different in a whole bunch of ways
I disagree. It’s perfectly possible to hold an internally consistent view that it’s wrong to execute a prisoner, both because there’s no reason to do so (the prisoner already being imprisoned) and because courts get the decision wrong too often (and/or because the courts aren’t trustworthy), while also believing that it’s acceptable to kill under other circumstances