Alexander McSouthers, also known as "Sandy," is the doorman in the story, but he used to work at the Westing Paper factory. There are a couple of points in the novel that indicate he was fired for trying to start a union at the paper plant. In chapter 21, "The Fourth Bomb," in the information about McSouthers, it says:
Alexander McSouthers. Called Sandy...Jobs: Mill worker, union organizer...Westing connection: Worked in Westing Paper plant 20 years. Fired by Sam Westing himself for trying to organize the workers. No pension.
Also, in chapter 14, Sandy is talking with Judge Ford. She asks him about his family and if he had trouble supporting them. He replies:
Not so bad. I picked up odd jobs here and there after I got fired from the Westing plant for trying to organize the union, but mostly I boxed.