What is the message Edwin Brock is trying to convey in his poem "Five Ways to Kill a Man"?

The poem "Five Ways to Kill a Man" by Edwin Brock consists of five stanzas, each discussing ways of killing people common in specific historical periods. It takes the form of a dramatic monologue in which the narrator appears to be discussing the matter with a cool, almost clinical precision. It is not an instruction manual on how to kill people but a meditation on human cruelty, conveying the message that our apparent progress in technology is not paralleled by moral progress. 
The first stanza focuses on crucifixion, a method that will, to many people, immediately recall the death of Jesus Christ on the cross. Thus at first it appears a form of barbarism that most readers will automatically condemn as they relegate it to a distant and more violent past. The second stanza describes medieval knights jousting, something that is glamorized in poetry but which Brock debunks by exaggerating the stereotypes of Arthurian romance. Next, Brock describes the horrors of trench warfare. The fourth stanza shows even greater technological improvement and depersonalization of killing in the form of dropping nuclear bombs.
It is in the final stanza, in which Brock talks about simply placing people in the twentieth century as the most efficient method of killing, that he reveals two things. First, writing as he was during the Cold War, the first part of his message was a concern that a nuclear holocaust and the "mutually assured destruction" policy of major nuclear powers was a threat to the safety of everyone in the world. Second, he is also suggesting to us that developing increasingly powerful military technology is not really a form of progress, as it creates the ability to kill more people more efficiently and puts our entire world at risk.