Actually people who don't live outside have those accents as well. His parents actually moved back when he was 1 or 2 years old. This is really on the lines of the typical accent of people from this subcontinent who are highly educated (via English), well travelled, well read etc.

I have a friend who went to UK and came back after 13 years. Spent most of the time at SOAS. Her accent didn't change at all. It is what it was when she left at the time of her bachelors. She did masters, PhD, and post doc there (the last one is still ongoing - not sure, some people study a lot).

But I see people coming from America in 3 bloody months and speaking English in American accent.