Maybe you need to pay more attention to the ceteris paribus. When you include that, it seems perfectly sensible to me.
Consider a world in which in 1945 Adolf Hitler will either choke to death on a piece of spaghetti or will be poisoned by a survivor of the death camps that bribed his way into Hitler's bunker...
Pop psych states that murder, especially first-time murder, induces lifelong psychological trauma in neurotypical adult people - and that, therefore, most of them lose more (I'm not saying "more utility") than they gain.
Clearly, that wouldn't be the case with the death camp survivor [1], but I can see a sane, relatively untraumatized civillian who'd volunteer for Hitler's post-war execution regretting their loss of innocence afterwards.
[1] I've heard that this was what happened with the commandant of Dachau and some of the SS guards there, who we...
If it's worth saying, but not worth its own post, even in Discussion, it goes here.