Mr. Monk Goes Back to School - S2-E1
Other mistake: Derek tells Beth to meet in their "usual spot" the next day at 8am. The next scene has Derek sitting at his desk and it looks like the kids are already in deep with their SAT tests. Beth falls at 8:25am (as per the clock in the testing room.) There is no way that Derek could have killed Beth, put her on the minute hand (later in episode on the Monk recap, it has 8:15am. If Derek was proctoring a SAT test, I don't know of any that start around 8:20 and immediately in depth.
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