Just wondering about this. My guess is probably not. The following from the Canadian Encyclopedia online piqued by interest in this:
In an effort to stem the influx of American "imports," the CRU sought to impose a residence rule. It soon became obvious, however, that the member clubs and leagues were not as adamant. The Grey Cup was gaining prestige and acceptance with the public. With the end of WWII and the resumption of the various leagues, the 1946 CRU meeting stipulated that each team could play with 5 American imports. Some teams, notably the Toronto Argonauts, preferred to play with an all-Canadian lineup. The Argos did so until 1950 and in the process won 3 consecutive Grey Cup championships under coach Teddy Morris (1945, 1946 and 1947).