According to the regulation a device which "muffles or stops the sound or report of a firearm" is not a prohibited device, it must be "designed or intended to muffle or stop the sound or report of a firearm". A fake suppressor which was designed for cosmetics and happens to reduce the sound is not automatically a prohibited device. In the case of fake suppressors, most are just barrel extensions with no intentional sound deadening devices contained, and therefore should be easily proven to be designed and intended for the look, not function of a suppressor.
"prohibited device” is under section 84 and means
(a) any component or part of a weapon, or any accessory for use with a weapon, that is prescribed to be a prohibited device,
(b) a handgun barrel that is equal to or less than 105 mm in length, but does not include any such handgun barrel that is prescribed, where the handgun barrel is for use in international sporting competitions governed by the rules of the International Shooting Union,
(c) a device or contrivance designed or intended to muffle or stop the sound or report of a firearm,
(d) a cartridge magazine that is prescribed to be a prohibited device, or
(e) a replica firearm;