I know you like playing the role of hairshirt, but are you really confident that this is true? That he would be paid as a 'resident of Sweden'?If he is living abroad full time his employer should be paying him as a resident of Sweden which will have payroll implications.
Pretty sure they'd just pay him as (tax) resident of Canada and the rest would be for him to work out. As far as I'm aware almost always payroll deductions done as if resident of Canada for wage work, with bias to keeping the withholding (income) tax rate at the higher level, and any refunds/etc worked out later.
That said, not a payroll expert.