The Swedes are not lapdogs. They simply agreed not to pass a boundary and both sides have honored the agreement. Relations grew from there.
I cannot speak for pirate leadership but I highly doubt giving up ports will be an option(at this point in time), given the general attitude of the pirate nation. At best you all may be allowed to keep the ports you have and expand elsewhere from those ports, without fear of the pirate nation capturing them. You'd essentially have a safe area around your core ports with added protection because of their proximity to pirate ports.
Of course, this is all just my opinion. If such a deal did occur, it could open the floor for more deals in the future, and more cooperation. Baby steps...it would be foolish to give away territory to someone who calls you enemy when you have them nearly entirely removed from the area.
Also consider what can the French offer the pirates? How can both sides demonstrate commitment to the agreement? If I anger anyone by saying these things I apologize, I'm simply trying to start a civilized conversation.