I have seen this happen in Nepal too.  Yes, in Nepal.

Anyone with mongloid feature are referred to as Bhoteys (Tibetans).  Just like this Mizo chap was made to feel like a foreigner in his own country, many in Nepal are made to feel like non-citizen in their own country.  

And just like it is not due to ignorance but to "looking down upon" when anyone is called Nepali in those circumstances, being called "Bhotey" is also same phenomenon.

Just something I observed.