You did start the insulting back when this discussion started in the other thread by insinuating people were stupid and/or insane for thinking this low life should be killed. And the part where you attacked the 'fairytale nonsense' may be one of very few times where I, a fellow atheist, felt defensive towards the religious since the guy was likely just using an expression without any real intent to bring up religion.
However in your favour I have at no point thought you weren't sympathetic to the families of the victims, I'm not sure where that came from. You are simply arguing that killing this guy after-the-fact is not the right course now. I just disagree with that. In cases like this where the crime is so terrible and the guilt of the perpetrator is beyond doubt I think the emotional response is justified and is probably the right and fair one. Also, I do believe most people directly affected will, in their heart of hearts, want this guy dead. This was an unforgiveable act, any who say they could forgive this is naive and/or a liar.