I think it's pretty clear cut and something that would be easy to define, such as having collected a paychqeue playing in a professional sports league or organization. Yes that means no Ray Ferraro. I don't know about the Rock, but easy enough to lump pro wrestling in there.
Most of that you don't need to worry about because these are gambling outlets targetting specific sports and will want premier players from those sports for those adds. So Wayne Gretzky, Conor McDavid, yes. Ray Ferraro, no. Dwayne Johnson and Oscar De La Hoya... what they heck would those guys be doing in Canadian provincial gambling adds?
Regardless though it's up to the province of Ontario to define their guidelines for advertisement as they see fit and if there's any issues then that can be brought to the supreme court. Let's just call this 'civics' rather than the forbidden 'p' word.