It was not just Pierre Trudeau as nine of ten provinces also supported the Charter which was modeled on Diefenbaker's 1960 Canadian Bill of Rights right down to the notwithstanding clause at section 2..  

In fact Pierre Trudeau invoked Section 2 when proclaiming the War Measures Act to deal with the FLQ during the October Crisis.

BTW it was Diefenbaker and his Minster of Immigration that got rid of the racial preferences in Canada's immigration laws  virtually abolishing the “White Canada” immigration policy on 19 January 1962 and opened up the refugee system.  Since the Bill of Rights had rejected discrimination by reason of race, colour, national origin, religion, or sex, the federal government could no longer justify selecting immigrants on the basis of race or national origin.