It sure was substantive! I'd never thought of the idea of using the death penalty as a punishment for crimes before reading it. And I certainly didn't know what his opinion was on whether a specific crime deserved death, and I was very delighted to hear it, and then imagine the punishment happen. It made me feel good.
Like it or not, the death penalty is perfectly within the norms of the civilised world; it's popular even where not allowed.
In this case, the only thing incompatible with civil, substantive discussion was … you.