I believe that's in Regulation SOR-98/206 s.4: "A chief firearms officer who issues an authorization to transport shall attach to it the condition that the firearm be transported by a route that, in all the circumstances, is reasonably direct."
and, here's a legal comment
Included in those regulations is a requirement that the route taken by the firearms owner, from home to range and back or from home to gunsmith and back or from home to border crossing and back, be reasonably direct in the circumstances. This is an area of law that has yet to be litigated, so there is no jurisprudence on it. All we have is that requirement on its face.
If Mr. Trudeau were asking me for legal advice, I would tell him that going to the grocery store with your pistol in your trunk is not reasonably direct in the circumstance.
-- Solomon Friedman, Firearms Law Expert, June 10, 2015, https://sencanada.ca/en/Content/Sen/...C/33ev-52219-e
The travel from your home to a shooting range or a shooting competition always has to be the most direct route. You don't have to map it out, but law enforcement will have to do what they do every day, which is exercise common sense in their judgment to map that out. But that's a requirement in law; it always has to be the most direct route.
-- Kathy Thompson, Assistant Deputy Minister, Community Safety & Countering Crime Branch, Public Safety Canada, June 10, 2015, https://sencanada.ca/en/Content/Sen/...C/33ev-52219-e
Good point.
Nonetheless, just because one law allows something, doesn't mean another law doesn't disallow it. We have to be in compliance with them all.