Yeah, they really published that. Here's the retraction.
They get a little miffed in the retraction:
Here’s what isn’t fair, though: Some readers seized this opportunity to accuse us of using this graphic to promote what they termed a specific liberal agenda on the topic of gun control. They saw our labeling mistake as a deliberate misrepresentation, one that made these weapons seem more dangerous. Let me say emphatically that this was a careless mistake, not an intentional deception nor bias. It is regrettable because we got a basic fact wrong, period.
No, you know what the issue is? The issue is that you're agitating for gun control and you haven't the foggiest idea what you're talking about. If you had even the most cursory of knowledge about firearms - or slings for that matter - or took a few moments to get in touch with folks who did, this never would have happened. But no, you think you're smarter than us - if those inbred hillbilly gunhumpers can figure these out, by golly us ivory tower eggheads can't possibly get it wrong!
But get it wrong you did. You identified a sling swivel as a bayonet lug/grenade launcher attachment - in and of itself an amusing slip - in your attempt to educate the non-gunhumpers what made those "assault weapons" so gorram deadly. ZOMG! Large capacity bullet clips! Folding stocks that allow the gun to fit in a shirt pocket! Bayonet lugs that allow you to add on a heatseeking missile!
In actuality, the stock means that different shooters of different sizes can share the same rifle without having to take 20 minutes to disassemble the rifle. The magazine is the same size as that which is issued to our police and military forces - 30 rounds is standard capacity; the magazines you wish us to have are low capacity. Words matter. And the bayonet lug? Really? Are drive-by bayonetings that big of an issue? Grenade launchers? Do you have any idea how heavily regulated explosives are?
Your ignorance of firearms is exceeded only by your arrogance towards those of us that own them...
That is all.