Don't worry about it. The Hmong language is not that important or is it to you?
As long as he can understand, that means he is still install with the Hmong. He can speak back in different language to communicate.
If it is real like that then it is an understanding but if he just refuses then all bets are off. I can't tolerate a faker, especially one that are too shy of their own culture. The only pass I can give is if they are mix and with that, I call it a confusion because the poor kid is confused to which language he wants to take upon.
Being bilingual has it's benefits because some jobs requires one to be bilingual to cater to their patients or customers. If you lose your own language, I am expecting for English skills to be like a white man. You talk without hesitation and with that, can take you places in a certain job market.
One job is journalism. They are azn on tv, training to speak the language like the white man an guess who they end up marrying? White folks like Connie Chung, the view chick, Lisa ling n Kelly hu n that one Charlie angel biatch Lisa Liu.