The theory is bunk. And it's irrelevant. They are violating the gun laws either way!
It is illegal to posess a firearm for purpose of self defense in Canada, regardless of how it is obtained. Criminals know this. Criminals WILL posess firearms.
Maybe now you'll see Dodger's point? Gun laws only apply to those who would obey the law. Not to those who won't. Canada's draconian gun laws didn't protect the 10 dead people from the criminal. It's WHY we have the 2nd Amendment. So our govt cannot infringe on our right to keep and bear arms. We have the RIGHT to defend our life and property. Canadians don't.
It's a crying shame...people slaughtered like sheep and the gun laws didn't prevent someone from obtaining a gun and using it. The same is true in the US and gun crimes are off the charts in cities and states with restrictive gun laws. You can also look at Europe and see where 130 innocent people were killed in Paris in 2015 and the Charlie Hebdo attack that killed 12 more. And there are many more but you get the point.
And it's irrelevant how someone obtained a gun and I'd be willing to bet this nut job in Canada didn't build one from a 3D print out, no more than the savages in France did. But even more telling is how silent the left is after the Canada massacre. It doesn't fit their agenda so they just dismiss it outright without any discussion. Kind of like what's happening with Biden and his accuser. They try to destroy a man nominated for the Supreme Court based on statements made by complete wackos without any proof but not a mention in Biden's case and there's more proof to at least add some validity to the accusations.
At the end of the day, I don't agree with these folks that come out of the closet and make these accusations 30 years after the fact. But this door was opened by left but somehow they feel it doesn't apply to them. And half the American public buys it.