I agree to disagree (or as we are saying in our language - you are not arguing whether the food is good or bad - but you fight). I would still call a chinese (han) person a chinese person whether no matter whether he/she is citizen of China or some other country. At least currently in our country private companies won't fire a person, if he/she says that.
In case of our small country - if you say that all other languages are equal - that will basically destroy our ethnicity. If you look at the map, you should know, why.
What if that hypothetical Chinese person prefers to acknowledge both the Chinese and (for example) American parts of their heritage? Should they be allowed to do that? Would you respect their choice?
I get your point about how making other languages official languages of Estonia could erase the language, although the counter argument to that would be Maori, where it took an act of recognizing it as being an official language of NZ to bring it back.