From my understanding of the legislation—and I too am not a lawyer—I think the provisions of Bill C-25 would apply to public company boards. If a company comes in and sets up a subsidiary in Canada and the parent company is offshore, my understanding is that they're not a public company in Canada. They're not trading on the TSX and not registered under the CBCA or the provincial BCAs, so I'm not sure that the law would apply to them.
On February 9th, 2017. See this statement in context.