Sure the dude could've answered it better but the interviewer was a douche bag for laughing at him. If I were the interviewee (Nepali diplomat), I would start talking in Nepali and when the interviewer is dumbfounded, I'd lough out loud at him.

Going to UN doesn't require you need to speak english fluently. I am not defending our diplomat's inadequacy but rather questioning the reason behind this snobbish interview session.