[illuminerdy]

I have no idea why you think what you posted has anything to do with what I said or the interaction that is being discussed. The Due Process clause is not the only source of the state's power to enact laws and regulate the conduct of citizens. The police powers of the government existed long before the Due Process clause was enacted.

But even if you take the position that the police are not REQUIRED to do anything (and I would disagree with that position), that does not mean that they CANNOT do anything. In this case, the police CHOSE (to use a term more suitable to your position) to investigate. And nothing precludes them from choosing to do so. Or do you take the position that the police are neither required to, nor can they choose to investigate when called?