That's a bingo! You can't really draw very much from the poorly framed data in this article. They selected these 6 countries by absolute number of deaths / gun

That's a bingo! You can't really draw very much from the poorly framed data in this article. They selected these 6 countries by absolute number of deaths / guns, rather than per capita; mix suicides with homicides; and don't include the overall number of homicides, which (as I think you're suggesting) could be used to tease out direction of causality. Moreover, n=6 lies in the realm of anecdote, not data. There are ~200 countries in the UN. If you want to know anything significant, throw all their gun ownership rates, homicide rotes, Gini coefficients, etc into a regression and maybe you'll be able to say something interesting.