I think writing poetry is more of a symbolic thing. It is not typical, but it symbolizes something that first generation Chinese immigrants want to do, or want to have, but couldn't back in China.
As to whether to take the manager role or not, it's just like whether to write in English. It is Nan Wu's personal choice. I think eventually we all 殊途同归, we will still be a "lemon" no matter how integrated we are to the American society.
In the novel:
Nan's son, Taotao asked his parents, "Can I major in French in college?"
"You should study to be a doctor", Pingping said, "What profession is better than save people's life?"
"I don't like medical science. How about art history or English? Can I major in art history?"
"Zen you will be a poor scholar for zer rest of your life", Nan said.
"I don't care."
"You don't care because we work night and day to make money for you, " retored his mother. "You act like rich kid who don't need profession."
Taotao turned to his father: "Did you tell me to follow my heart? You said, "As long as you do something well, you won't starve.'"
I believe a lot of Chinese parents can identify with this. We work hard to get security for ourselves, and to provide a better life, A Free Life, to our children, so that they can follow their heart and lead a better life than ours. In the novel, I think Nan Wu later realized that he should follow his heart too and writing poems in English is his “Free Life”.