The dwarf trader in Keldagrim is the only one thieving npc who is not walking around, that's the purpose. Furthermore, you can't just set up the autoclicker, because other dwarves are overlapping him from time to time and the mouse is following those npc, so there should be an option to input an ID (every trader has the different one).
To sum it all up it's really good exp and additionally money for a simple script.