In Things Fall Apart how does Uchendu establish his authority when he addresses Okonkwo?

In Things Fall Apart, Uchendu establishes his authority when he addresses Okonkow by calling his sons, daughters and then Okonkwo, who is is nephew, togeteher. He puts forth a challenge to any of them to speak up of they believe they know more than he does. None of them speak up at that time. Then, he asks Okonkwo a question that he does not know the answer to, when Okonkwo replies that he doesn't know the answer, uchendu calls Okonkwo a child.