The framework for this story is likely a reference to the idea of a tax-collector, someone who is employed by a political majority to cause havoc and harm amongst his brethren. Why? Because that's how he earns his money. It's a job. For Henry Park, this means selling secrets to entities that are trying to diminish the effect of Korean Americans on their government and society. That means that Park is literally profiting from the disenfranchisement of his own people group. This willingness to harm others comes from a sense of self that is detached from its origins as an ethnically Korean person. In other words, in the absence of his father's hard work to preserve his culture and worldview, Park is left to decide for himself how much he values his identity as a Korean, and the answer is fairly obvious: he doesn't.
Look at the note that his wife left him on her way out of the relationship. It's a biased, scathing list of his faults and failures. As a symbol, the list comes to represent his awareness of his shortcomings, and his self-esteem issues continue. Notably, his self-esteem issues cause him to do evil to others who are like him. That's an especially poignant feature of the plot.
The subtle argument of the novel is that Henry himself gets to choose how much he prefers his identity as an ethnic Korean. It could have been meaningful, if Henry were in the business of celebrating himself, but since Henry's sense of self is largely pessimistic and full of self hatred and doubt, he completely forgets that he's allowed to celebrate his identity without blindly obeying traditions that don't work anymore. In other words, the novel is about his journey in light of his self doubt as an immigrant and as a citizen.
