I think I missed the memo on that. It would be interesting if you could substantiate your outrageous claim with some facts or statistics.
Pakistan was created on the basis of “Pakistan ka matlab kia, la illaha illala” so assuming these “upians and cpians” were muslims, did it occur to you that there might have other reasons that drew them to Pakistan? Hindus and Sikhs continued to pour into India well after 1940s and it was not exactly the lure of jobs in India that propelled them to leave their ancestral lands for good.