France can ruin Italy's plan by offering unwanted support to the self-standoff and sneaking into the Mediterranean when one of Italy's moves then succeeds unexpectedly.
France: Army Gascony SUPPORT ITALIAN Fleet Gulf of Lyon -> Spain (South Coast).
France: Fleet Spain (South Coast) -> Marseilles.
France: Fleet Marseilles -> Gulf of Lyon.
France: Army Burgundy SUPPORT Fleet Spain (South Coast) -> Marseilles.
France: Fleet Portugal SUPPORT Fleet Mid-Atlantic Ocean.
France: Fleet Mid-Atlantic Ocean HOLD.
Italy: Army Piedmont -> Marseilles. (*bounce*)
Italy: Fleet Gulf of Lyon -> Spain (South Coast).
Italy: Fleet Western Mediterranean -> Spain (South Coast). (*bounce*)
Italy: Fleet North Africa -> Mid-Atlantic Ocean. (*bounce*)
Is there another way that Italy can still blockade the Mediterranean with only three fleets? Can he rearrange his position (possibly adding additional armies) to form a solid barrier?