> I am not required to respect the police.

You are one citizen. The police represent the other million citizens. They have the monopoly on violence, so that all the other citizens can't do that. I think this is way better than every citizen caring weapons and doing self-justice. Even when the police is going crazy, that is still better than civil war. They do have checks and regulation even if they don't always work, the other citizens haven't.

That being said, I can absolutely see, how you distrust the police. I can't imagine what justification the police gave to their superiors in your case. I would expect public outrage if this became public, but maybe your country truly doesn't care.

Of course you shouldn't report such issues to a corrupt militia, which your police seams to be posing as. However that is not what I would call a police and it should be reported to the police if you had such a thing in your region.

When you ignore children with violent intentions this will lead to a stabbing or shooting later on. The police will treat a single claim very differently than recurring threats for violence. Informing the authorities early one makes them able to send therapists the first time. When they only ever hear about problems once things went violent or even only at the time of the amok, they need to send the violent force on the first occurrence, because they can now only try to shield the victims not help the delinquent child.