The police still have a job to do which is to serve and protect. Imagine if that boy had been yours and the cops thought the situation peculiar enough to question the guy, what might have otherwise happened to that child. As it turned out the kid was his, but if the situation had been different. . .Under our laws here in the United States, No one is required to show an ID to a cop if stopped and asked.
We are not required to carry papers of identification on us, to show the Gestapo when asked....
I do not blame the officer at all for questioning the man. And the cops were polite and friendly and non threatening in the initial contact. It was only when the guy was not polite or friendly and behaved even more suspiciously that there was any kind of confrontation.
No we do not have to carry our ID when we go walking. But we are required to have our driver's license and registration and insurance information in the car with us and to produce them when requested. I have to provide ID when I go to the courthouse, go to the FBI building here, when I file a police report or ask for one, etc.
If the officer had asked me for ID when I was out walking--maybe I fit the description of somebody reported committing a crime or something--I would give him my name, tell him I lived nearby and we could go to my house to get the ID. I do not see that violating my rights in any way.
I do question whether taking the guy down to cuff him was necessary but then I don't know all the police protocol/policy in such situations either. Having police officers among friends and family, I am very aware they are allowed to protect themselves too.