I'm new here but I'm good at systems. If you don't want someone you know only so they can be a Captain with you to have access to your facebook pages do what I have done. Create a folder for people who are just pirates or gamers. Then set your access to customize & exclude all from this folder. You do this by clicking the pencil to the right of friends.Just remember, as soon as you confirm them as friends to put them into the folder.
Yeah, they are called groups in FB and most of us restrict access for some stuff for people we put in those groups.
I just delete them after they've accepted my Captain invite. It seems people don't need to be in your Facebook Friends indefinitely to be one of your captains.