I think what he meant was a response to your question of why don’t we turn him into fertilizer. Their insinuation that turning people into fertilizer would go against due process and the right to trial. The use of “silly” I believe was sarcasm. However to be fair you could be saying that the outcome of a fair trial and due process would be a punishment in the form of turning him into fertilizer. However I think we can make the assumption based on their comments that they are against capital punishment. Either way I think we can all agree that his actions have no place in our society and that he should meet with the full force of the law for his crimes.