The objective is social fukkery.
It's something we have not seen in a game yet.
Most games are built with the "game" in mind. SOT was built with social fukkery in mind. The story/experience you posted here is "it".
People who are down for that will find a lot of fun with this game.
The fukkery is actually A1.
When you see another pirate ship over the horizon.
When you tell your squad to watch the ship while you drop off the loot and he shoots himself onto the island... 5 minutes later you see your ship sailing away.
When you're on the chase and get caught be the kraken.
When a guy tries to sneak on your ship and you walk out of the hold and hit him with the Draco.
When the highest nikka in your crew steers into the island.