Equinox is correct, not just Unioners, but all of the criminal factions in Rheinland originally started as ideological 'terrorists', but the impossibility of their situation thanks to the Rheinland Military as well as a lack of funds and supplies forced them to use piracy to achieve their goals. This is even true of Bundschuh.
After some time, these terror groups began to consider the money made from piracy as their goal, as opposed to a means to an end.
For more info on Unioners, speak to Kress, he knows them well.