Yes, the above statement is very much true. The poet has indeed shown throughout the poem how the ways of killing has ‘improved’ through the ages. Towards the beginning of civilization, when there had not been the scientific progress, people needed to carry a plank of wood, nails, a cloak, a sponge, some vinegar and one man to hammer the nails home. The crucifixion of Jesus was a cumbersome way to kill a man.
 
But in the middle ages, men needed to take a length of steel, metal cage and white horses to fight against one another and pierce the metal cage one wears. This was an improved version of killing from the previous one.
 
Then, with the scientific discoveries, it came down to gas warfare that was used in the World War I for mass killings. Again, in the World War II, an age of aeroplane, they just needed to fly and drop an atom bomb and press a small switch to destroy an entire city. 
 
In the final stanza, the poet regrets that living somewhere in the middle of the twentieth century itself is enough to kill a man bit by bit by its curses like poverty, hunger, joblessness, ignorance, disharmony and much more. A poverty stricken and war-ridden world is what the progress of science has gifted us finally. This is no fault of science itself. But the use of scientific inventions for the wrong cause by some greedy people has reduced the progress to improved methods of killings. 
 
Even in this twenty first century world, killing a man is probably easier than anything else. Fire arms and explosives are now readily available to even common people. Terror activities have been the biggest challenge for peace loving citizens all over the world. The blessing of science has been reduced to its curses. This is what the poet draws our attention to.