...the guns need to be stored in a way that they can't be stolen...
No such thing, which is the real weakness in the argument.
There are 5 guns in my house: 2 Remington pump action shotguns, a single-shot Winchester shotgun chambered for 3-inch shells, a 1917 vintage Lee Enfield .303, and a single shot Cooey .22. They're all properly registered under Canadian law, properly stored as per the regulations, and I've even gone one better: the firing mechanisms have been removed and stored separately. So even if somebody steals them, they're useless unless they can also find and steal the firing mechanisms. They'd have to pretty much take the house apart to do that, the parts are small and very well hidden. Ammunition is stored in yet a third place. I do that because it ensures it'd take me at least 15 minutes to assemble and load a gun for use, so no matter how drunk or stupid I might get, I won't be able to use one in a crime of passion. I haven't used any of them but the .22 for over 15 years. I don't live in Toronto, for which I'm grateful, or anywhere near it, but the reasons I have for owning those guns would also work legitimately in Toronto.
The .22 is for rats at the lake. Two of the shotguns I own because I used to hunt ducks and geese a lot. They're good to eat. The third shotgun came to me from my father's estate, who owned it for the same reasons I got mine. I've never used it. The .303 is an heirloom, a military-issue weapon carried by one of my grandfathers in World War 1. I've never used it either, and in fact I don't even know if it's safe to use.
Guns for home and personal defense is a completely stupid idea that hurts more people than it helps, a specious claim due mostly to the NRA, which along with the U.S. Supreme Court has done a fine job over the years of distorting the intent of the U.S. Constitution about the right to bear arms. That clause is clearly about maintaining a militia, from the days when the members of such an organization would have had to provide their own weapons. Times have changed.
The only reason you might want a handgun in your car is the knowledge that the guy in that other car you just inadvertently cut off or otherwise somehow managed to severely piss off might have one. If you can be confident he doesn't have one, as you can be in Canada, then you don't need one either.
Hearing from Americans about how personal gun ownership keeps them safe from criminals and bad governments just doesn't wash. One of the highest murder rates in the world, highest rates of violent crime involving guns, a trigger-happy President who thinks it's okay to go shoot up a helpless and sick little country and lie about the reasons for it...
Yeah, U.S. gun laws really work superbly...