I am still fuzzy on the point of the article. It is my understanding that having a gun in the city is illegal so, the persons carrying the guns into the city have broken law number 1. The assumption being that IF the legally registered firearms shop did not sell the individual the gun following LEGAL processes (background check etc), then the crime would not have occurred? I think we need to re-examine our expectations that making something illegal will stop the activity.
What they’re trying to say is that their totalitarian gun laws would work if only those who refuse to live in the cities would be under the same totalitarian rules.
McDonald v. Chicago, 561 US 3025 (2010), ring a bell? It might be illegal to carry a gun (depending) in Chicago, but not possess one.