It's actually not rocket science. Even if the workers have open work permits, if good employers are offering good working conditions and good accommodation, the workers will want to work for them and won't look elsewhere, quite the contrary.
On the other hand, if they're employed by people like Jean Lemay, they'll just quit their jobs and go to work somewhere else that offers better working conditions.
Incidentally, I sit at the round table with employers. I tell them every time that the open work permits issue isn't very complicated because if they offer good working conditions, those workers will want to work for them, not someone else.