Mr. Monk and the Voodoo Curse - S8-E7
Plot hole: The murderer planted the voodoo dolls after the accidents to make them look like victims and cover up her murder of her uncle, but none of that was necessary! She uses an untraceable poison on her elderly uncle to make it look like a heart attack. So if he'd died...they just would have figured it was a heart attack! No suspicion would have fallen on her anyway, the entire voodoo thing was just needlessly complicated and only exists for the episode's plot.
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