I think it depends on the GA, when AC had the YYZ-AUS route running on the Jazz CRJ-7's I called in and asked to use an NAU (was during the summer program) and was confirmed. As I was going to a conference in AUS that all of our Canadian based employees were also going to, the flight was very oversold. When I went to the podium to hand over my cert the GA told me that I wouldn't need it as she was going to give me an OPUP anyway. I asked her if I could upgrade my manager using the cert and she happily did it for me and took the cert since he had no status.