That's fair enough, but he's pointing out the consequences of your beliefs. The crux of the objection is that you position yourself in opposition to the discussion of any other justification for abolishing the death penalty; it is not that the death penalty must be abolished, but that it must be abolished for a specific correct reason. This presents a relationship between the death penalty and your beliefs where it seems to your audience that you wish to abolish the death penalty not due to any urgency regarding its consequences, but because of your insistence on imposing your will on others.