I am not commenting on the relative status of murdering a child vs. anything else. That is you trying to "rank" it somehow. To me there is Evil, Not-evil/good and Good. And I find your reasoning to be wanting in defining the murder of a child to be "good"
Well that's fair. I think the kings of Loire disagree though, particularly when it comes to heathens/heretics, just because a death is regrettable doesn't mean good can't come out of it, and in this case the good is both political AND metaphysical.