Actually, city policy is that you can have booze on city property as long as it is not open. An example would be if you bought a bottle of something at lunch and were taking it home, or if a department were raffling gift baskets that contained a bottle of wine.
Maybe that's how they do things over at City Light, CVdR. I would think twice before browsing
the wine section of a grocery store while at work. If my co-workers store bottles in their desks, they're brave / dumb / unaware of how much trouble they could get into.
Imagine pot isn't wine in your analogy, but instead it is a loaded gun.
More seriously: Holmes is fully aware of the looming Federal Drug Free Workplace nightmare. His department will have to defend any city employee caught between our new weed tolerance and the Feds' stupid DARE-era policy. If Holmes doesn't wake up sweating over the standard practice
he just established, he isn't very far-sighted.