Does that person really have the necessary skills if they are not bilingual? That's the problem. We always say that bilingualism is essential, but then it goes to the bottom of the list. It should be at the top of the list.
We have to stop saying that someone who doesn't speak French or English still has the necessary skills. No, that person does not have the necessary skills. We have to change the way we look at and analyze the situation. We have to clearly indicate what the essential skills are and, as the case may be, determine that a given person does not have the necessary skills. Then, we have to proceed as any good employer would: If we really want to hire that person, we have to find a way for them to acquire the missing skills. That said, the person should acquire those skills before they begin in the position, not after. Acquiring an essential skill after the person is appointed should be an exception, in my opinion.