This is a very complicated issue with meanings drawn from differnent acts. My personal feeling is that bullion coins are not collectibles. The fact that they trade above their face value is not the determining factor. From memory there is a section in the GST act (it may be a differnent act) that talks about whether the coin trades as "a function of spot" not above (or below) spot.
That is, when purchased it may have cost x + spot. As long as when it is sold you would get x + spot then the coin trades as a function of spot. The overall 'spirit' of the legislation is that they are trying to class numismatic coins as collictibles and have the collectible rules apply to those. IMO the intention of the legislation is not to catch bullion coins with a face value but rather numis stuff.