Momon is one of the leaders in the Tribunal, on Ibara, with Genj and Drea. Jen Remudi also used to be on the Tribunal. The Tribunal is like the government here, and decides whether a person that has done something bad will be banished from Ibara, or if they will do hard labor. In one case, for example, Siry Remudi tried to steal something from another villager, and when he was caught and brung before the Tribunal, they gave him the choice of watching Bobby Pendragon (who they thought may have been a Flighter, as they didn't know him), or doing a year of labor with the fishing crew.
This shows how heavily they can weigh the choices, as watching Bobby probably wouldn't have been long if he had stayed on the island for a while, while working on a boat that was fishing for a year probably wouldn't have been as short.