Mr. Monk Goes Back to School - S2-E1
Factual error: In the cold opening, Derek said that his wife is very smart and got a 1680 on the SAT. This episode takes place in 2003, the writing portion that was added to make the max (2400, not 1600) was in 2005.
Answer: The two men are trying to work out a secret deal between them without involving the union, which means the workers' interests aren't being represented and defeats the whole purpose of a union. The mayor would lose labor's support and Cusack's union troubles would just be starting.
Captain Defenestrator