Ehhhh, honestly? I can buy into the idea. Most of the settings in Zorro have always been this downtrodden view of Mexico; even the large places that the bad guys run. Those are more like fortified castles. Zorro was always kind of a wild west setting, so moving it over to a post-apocalyptic setting is pretty close to interchangeable.
Added at: 07:25
Of course, whether that interchangeability means it'll be actually good is another thing altogether.