Mr. Monk Gets Cabin Fever - S3-E12
Other mistake: When Stottlemeyer is about to eat his cake he is looking at Monk. Shortly before he starts to pick up a piece of cake you can see he is pretending to chew a piece in his mouth. Throughout the scene you can see Stottlemeyer's face and the cake. At no point before he pretends to chew does he put a piece in his mouth.
Mr. Monk Gets Cabin Fever - S3-E12
Other mistake: Kathy says "I'm going to get me one of those new Le Barons." Chrysler discontinued the Le Baron in 1995. Since the episode is from 2005, she should have said Sebring.
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