Earlier quoted context omitted.
Death sentence is absolutely not too much. It's an extraordinarily effective deterrent (see Singapore), and I don't know where the narrative comes from that it's not. Some people simply need to die.
Feels weird to get into a high-school debate about capital punishment here, but in essence: (a) Sometimes the wrong people get convicted. In this context, irreversible punishments suck. (b) “We’re going to kill you because killing people is wrong” is a weird look.
(b) It's not. Killing people that are evil is fine. Killing babies is wrong. You are intentionally simplifying the moral argument here to "killing people is wrong."