After serving Voumi for so long, only a few lucky ones were not put in positions where they had to hurt innocents, including fellow Terrans.
They were Terran but they might not be innocent, and they had to determine whether they'd have to serve a sentence (likely as guards with extremely long work hours and with pay cuts, if the crimes were not too harsh).
Depending on their transgressions, their salaries might be fully withheld for a while. In a sense, this could be part of a community service because they served the enemy, even if they had been forced to.
To be fair, it was also in consideration of the Voumi Terrans' psyche. If a person truly had a conscience, then this type of punishment was something they'd be willing to go through, and more, just to avoid depression.
