If a judge determines the man had reasonable cause to believe the boy was stealing the bicycle then he has a legal right to restrain the boy until police arrive. And he will not be guilty of a crime as long as a judge determines the man did not use excessive force.

If a judge determines the man did not have reasonable cause to restrain the boy or the man used excessive force or was motivated by racism, then the man could be charged with assault.

You presume assault, but I am unaware that a judge has made that determination. I do not have all the facts and neither do you, I suspect.

By the way, where did you get your law and psychology degrees?. Psychopath is a clinical diagnosis and assault is a legal one. For me, I believe in "due process" and letting the courts decide, based on the facts.