That's an interesting posit, but I wonder if it's strictly true. In the dark ages, siege engines catapulted plague ridden corpses into fortified cities in an effort to infect the defenders. Obviously, the history of biological warfare predates Mr. Franklin, and as an educated man, either he or his military compatriots such as Washington would've at the very least, "had some concept of WMD." Maybe not nuclear weapons, but certainly I would be interested in researching his thoughts on the subject of civilian oppression during wartime.
I submit to you that Ben Franklin did not have the slightest concept of either the magnitude or the rapidity of the destruction that modern man can inflict. There was nothing in his frame of reference to compare.