From the way that Okada portrays Ichiro in this book, it makes sense to infer that Okada himself was glad of his decision to answer the questions with a "yes-yes." A reader can infer this from all of the troubles that Ichiro faces due to his "no-no" answer.
In the book, Ichiro has refused to swear allegiance to the US or serve in its armed forces. This causes problems for him that are both internal and external. Externally, Ichiro runs into trouble with other Nisei who answered "yes-yes" and with society in general. Internally, Ichiro is very conflicted about who he is. He knows he is different from his more Japanese parents (especially his mother) but he has answerd "no-no" and so he is not truly American.
From this, one can infer that Okada's "yes-yes" answer helped him to feel more American and to resolve the tension between America and Japan that Ichiro clearly feels.