While it is true that health Canada has stringent standards, I believe that the material you are looking at is out of date and related to the product that Health Canada used to sell directly via Prarie Plant Systems (now an LP in its own right: Cannimed)... So the discussion of irradiated dried marijuana related to the product PPS was selling at that time.
It is my understanding that it is not a health Canada requirement that the product be irradiated, only that it meet the various specific quality control specifications.