In an era where right-populists and parties are getting more popular and people like Wilders, Trump, Farage etc. and their ideas get accepted more in the mainstream, it’s hard to fully accept the country you or your (grand)parents have migrated too as your own. Even if it’s the minority we’re talking about. Identifying with the country of birth or you parents country makes that easier.
I’m not saying that goes for Iwobi too, he could have different reasons for choosing Nigeria, but this what you’re saying is too easy.