Since the police are the enforcement arm of Capital why would they join forces with anyone seeking to depose Capitalism? All branches of Govt. are subject to politics and having a 4th Branch made up of cops is a horrible idea. The police are the gun in the hand of the Judicial Branch.
Let's get the Capitalists on the side of the Socialists while we're at it. After all if the Capitalists and Socialists weren't enemies society could easily implement true socialism, right? Seems too elementary, doesn't it?
The police exist to help enforce private property rights, the cornerstone of Capitalism.
If you imagine you could get cops, as a coherent organized group rather than as individuals, to join in a fight for Universal Health Care I'm all for it. Good luck.
John Thornton