Why does okonkwo think of Ndulue as a strong man?

Nwoye begins emulating Ikemefuna, and outwardly showing stereotypical masculine qualities, like grumbling about women and their troubles, feigning annoyance, and pretending he no longer cared for stories his mother and other women told. He was sent to do more difficult masculine tasks like splitting wood, and pounding food. Nwoye also began listening more to his father's stories, including those of Wrestling and war.