But he didn't just go to Pak for a holiday.It's not like an Indian going to live in Australia or something like that.He was a Pakistani citizen He never played intl cricket for Pak possible because :
1.He was well into his late 30s post partition (was 42 when Pak played their first test)
2.He wasn't good enough at that stage to make the side
He did play domestic cricket for Pakistan though
From wiki -
Shaikh Mohammad Nissar pronunciation (help·info)(born August 1, 1910, death March 11, 1963) was a cricketer, who played as a fast bowler for the pre-partition Indian cricket team and domestic teams in India and Pakistan.[1] He was born in Hoshiarpur, Punjab, and is considered the fastest pre-partition Indian pace bowler. He was arguably one of the fastest bowlers in the world during his time.
Indian batsman C.K. Nayudu claimed in writings that during his first spell, Nissar was faster than Englishman Harold Larwood, who terrorized Australia in 1932 in the infamous Bodyline series.
Nissar along with Amar Singh formed an Indian fast bowling duo that was considered one of the best in the world during the 1930s.
Outside of cricket he was a tribal leader of a large Pushtun tribe and also a pro-Pakistan leader. His memoirs are being compiled and include letters from Mohammad Ali Jinnah, Lord Mountbatten of Burma, and Gandhi. He was one of the founders of the Pakistan Cricket Board (PCB) and considered to be the first Pakistani cricketer.Recently, the cricket boards of Pakistan and India inaugurated the Nissar Trophy.
He migrated to Pakistan in 1947 and died in Lahore in 1963.