Churchill feared that Mussolini would be replaced by someone competent.
I kinda figure Mussolini was pretty much not worth the time and effort by July of 1943 when this plan was suggested - he had accured so much win by then that the Italians booted him on the 25th.
*Mussolini has been eliminated.*
Mussolini: lame
Roosevelt: gj Patton
Patton: thnx