In this wonderful article in italian on the origins of this recipe the author finds out that indeed before WWII there is no mention about this plate. So it is probably true that it has been invented when Americans liberated Rome in 1944. The fact that one of the ingredients is bacon that was to be found easily in those days explains how it all started. In times where everything was missing , why not to use what was readily available ( egg, bacon and cheese) in a creative way to create a new pasta recipe?
It is interesting to see that the search of the author of the article can be done by anyone using a little known search possible with Google. It is based on a data base built from a sample of digitized books.