Customs gets away with this too often, and expect the victim will wear down and give up.
If it is prohibited, it won't be allowed to enter the country... if it can be flicked open, it is prohibited, same as a switchblade or a balisong. Also, it's a tribunal deciding, not a public court of law, so it's entirely up to them. If they can flick the Benchmade open, you will only get this result:
"For the foregoing reasons, the appeal is dismissed."
The only option would be to ship it out of the country - however, since it is now a prohibited weapon, I believe you will need to find a shipper who is allowed to export prohibited weapons.
"You may export the properly reported goods at your expense under Customs supervision, forfeiting your rights to an appeal."
If this statement is correct then it should be fairly straightforward for you to show proof to Customs. Then if they decide your knife is still prohibited that'll open a whole new can of worms for retailers and the manufacturer.
Then of course there's the old adage: It doesn't have to make sense; it's government policy.
They don't consider that to be a factor:
"With respect to Mr. Hasan’s argument that identical knives are available for sale in stores in Canada, the CBSA referred to the Tribunal’s decision in Wayne Ericksen v. Commissioner of the Canada Customs and Revenue Agency where it was held that this argument did not constitute a basis upon which the Tribunal could classify goods."
Besides, if a police officer walked into a random "Kutters" or "House of Knives" and started attempting to wrist-flick all the knives open, anything that he could open would be a prohibited weapon.