Because of the way the store tables were initally defined, there is no way to mark US territories as part of the US and therefore not restricted by the strong encryption export laws. This keeps places like Puerto Rico from getting copies of non-exportable products.
The store code has been changed to allow exportable products to be shipped to all US territories. The territory MUST be selected from the Country menu rather than from the State menu (the state menu should have "Outside the US/Canada" selected since FedEx treats US territories as separate countries. Additionally the only shipping option available will be FedEx international priority (FXIP).