It's 100% legal to possess and use in Canada.
Not the point.
Not about possessing, but importing. It's perfectly legal for you to have it and use it.
Legalities are 1 thing, what the Govt has the power to do is another story altogether. Secondly, your legal argument nets you merely a schedule "F" form to fill out. Not my opinion, that's what factually happens in the real world, and has happened without variation to the rule.
The fact remains that Health Canada's regulations are followed by Canada Customs which seize e-liquid nicotine shipments and there is not a blessed thing you can do about short of spending a fortune on a lawyer. Perhaps you feel should that ever happen to you, you are just gonna go right down there fist on the counter telling them they have no legal jurisdiction and to let your shipment through immediately? They won't, they never have, they never will ... because you haven't filled out schedule "F". You may feel otherwise, and I hope you are right, because you would be the very first one ever to do so and I wish you the very best of luck.
Reason and rationality dictates that legal issues can be calmly sorted out with another. You are dealing with unthinking bureaucrats who are under regulatory order to do such and such. And they follow those orders.
I have yet to see anything other than every 'John Wayne' here bucking the system in the end do anything but lick his wounds. But like I said, best of luck should it ever happen to you.