If a Pirate has been placed anywhere next to your OPEN shipping route does that prevent you from closing your shipping route? (ie. on your next turn you will build a settlement on an island, but someone puts the pirate adjacent to your route before you get to place the settlement.)
My reasoning was that you may not be able to place the settlement because the the placement of the pirate would prohibit ships with supplies through to the destination settlement. I could not figure out if that is the principle to the rule or, if i am making a leap.