Hindi is not even spoken in south india. Most people there do not know or do not want to talk in hindi. Because of similarity of language the nepali speakers, urdu speakers, maithili, bhojpuri speakers may understand and be able to speak hindi without much problem... Your logic is twisted. There is not national and international language... language is just way of communication... if two people communicating are okay with it third person has no reason to advice what could be better language to use. People in west bengal of india speak bengali which is national language of bangladesh, national language of nepal is also spoken in india and there are nepali channels broadcast in india too... I speak urdu with my relatives and I dont think it is against national unity or whatever.... So if maoists speak nepali while killing you will you thank them for being nationalist or would you refuse some non-nepali speaking people from helping you in that instance?