I think he means what if the Union or Confederate Governments paid Famous (Imfamous) Wild West Outlaws to stir up trouble in the western states during the time of the Civil War.
Essentially Bandits were the Land Pirates. So Bandts paid by the governments would be Mercenarys-not Pirates. Unless you view the deserts and wide open plains of the West as a sort of Land Ocean then you could say they were Pirates.
At the timeperiod in the Union they had the Pinkertons, so it would not be far-fetched for either side to pay outlaws to stir up trouble.