The accusation that the police are surveilling union organizers is extremely troubling, and harkens back to the early 20th century when cops killed union organizers. The police should stay out of such political matters; especially if they expect their continued funding to be above political reproach.
Given how prevalent police unions are, and how incredibly quick they are to raise complaints, you'd hope for more self-awareness/solidarity and less hypocrisy.
It might be worth reading about how police performed aerial bombardment and gunned down union workers during the labor movement (late 19th, early 20th centuries) in the US, notably the Battle of Blair Mountain [1]. Even though this nears over a hundred years worth of distance, the effects ripple through today.