I caught hints of it earlier on as I was reading and didn't actually notice who said it, but I'll address it anyway:
The use of force continuum moves in both directions. If a person's statements and actions at one moment convey intent+means to cause death/grievous bodily harm, but a minute later that same person's actions no longer show that intent, but rather intent to escape, the calculus of what is reasonable force changes.
I.e., if someone breaks my face in a severe assault and I believe he's trying to kill me or maim me, I can kill him. If I don't kill him, and he stops attacking, turns, and starts sprinting aaway and shows no continuing or resurgence of intent to kill/maim I cannot legally kill him in self-defense. Where precisely that line of intent appears is up to first, the authorities who choose to prosecute, second, the prosecutor, third, a judge (and/or grand jury), and fourth, a judge and/or selected jury.