You make it sound like foreign coaches are doing this just out of pure goodness, or that foreign coaches will stop taking Japanese skaters unless Tran receives citizenship. The reality is noone forced them and they are being compensated for their services and in some cases very well. It is a mutual beneficial arrangement and really has no bearing on Japanese policy regarding citizenship.
How many years has Tran represented Japan ? 5 years ongoing and he still doesn't speak the language. Japan has enough problems now that average Japanese person doesn't care about Tran. Japanese cares about the nation and unity. People keep making circular arguments of what about this, or why not this, or how come that, but the bottom line is he won't get citizenship.
So that means people can't express their opinion on why he should? I don't know why you find it so terrible that people are expressing their opinions on why Tran should get citizenship. It's not like the Japanese government reads this board. (Or do they? )
From where I sit, even if JSF/Tran fail, they will have at least had the opportunity to open some dialogue on the topic of citizenship and national pride. I don't see that as a bad thing.