Even though CX Canada is a HKG entity, the Canadian authorities rejected CX's application for foreign employer status. Hence the decision that CX has to pay the employer portion of the Canada Pension Plan and Employment Insurance contributions. Also the CRA, in one of their latest communications, clearly states that CX Canada is considered a Canadian employer. However, the HKIRD has a different opinion in terms of taxes.
As such and as far as I know all Canadian laws and regulations apply to CX Canada and it's employees (the pilots) equally as to any other Canadian employer. The fact that CX Canada was setup as a HKG entity does not make it a foreign employer.