With even a basic history of labor power under capitalism it's clear that police are one of the greatest threats to organozed workers due to their role enforcing the capitalist status quo.
In the US police are often members of a union, and collaborate with the strikers, causing companies to hire professional security companies. Honestly, I have a hard time feeling much compassion for companies where the workforce unionizes: most of the time unionization is a relic of terrible management behavior over a substantial period of time.
Don't expect a wolf in sheeps' clothing to baa.