1Lord1Faith,
In principle, have no problem agreeing with claims that applying the death penalty equitably presents prudential challenges, and for that reason, should not be permitted in a given circumstance. But, that is different than saying we can’t define the term.
Traditional Catholic teaching on the death penalty involved much more than mere social self-defense. Current church teaching on the subject since Evangelium Vitae has never unambiguously clarified how the other traditional attributes of the question (retribution, deterrence, and rehabilitation) can ostensibly be summarily dismissed in preference of social self-defense.
The use of the self-defense analogy limps anyway as in the case of personal self-defense, the self-defender may not morally or legally use lethal force once the aggressor is prevented from committing further harm. In the case of traditional Catholic teaching on the death penalty, the aggressor is killed even after being prevented from doing further harm.
So anyway, to get directly to the point, Pope Francis’ amendment states that the death penalty is inadmissible because it is an attack on human dignity (as quoted above). You denied that it is. Therefore, you disagree with Pope Francis. The amendment does not say the death penalty is not necessary for some given reason (which is what past popes have claimed), it says it is an attack on human dignity. It is not outrageous for people to question and ask how this is reconcilable with past teaching.