Firearms News complete article:
Aero Precision's M4E1 7.5-Inch Atlas S-One Pistol Upper-
Increase Your Odds of Survival When Getting Out of Dodge

Video here (non-YouTube)

5.56?  Knock yourself out.  I'll pass.

Not going less than 10.5” in 5.56.

From the article:


I don't really get this point.   As a travel/back-pack gun, your goal is to get home.  
If you have your gun with a mag in it, along with another mag or two, (and your EDC) you are probably not running out of ammo unless you somehow managed to find yourself in a massive shootout.  If you are already in a massive shootout on day 1 of SHTF, you are not going to be able to walk into a store and buy ammo regardless.

I guess the point is IF you run out of ammo, 5.56 is a lot more common than .300 BLK will ever be - and that's true. Only two or three mags? The article is about SHTF not EDC situations. The article also mentioned getting ammo from other places than a store. I don't think the writer is just talking about an emergency situation and you are at work 10 miles from home. He mentioned distance travel.

He talks about away from home/travel/riot/on a plane, etc.  It sounds like a "get home gun" during SHTF instead of a SHTF gun.   If you are 150 miles away from home and something big breaks out, I would assume your #1 goal is to get away from the situation and get back home.   If you are in rolling gun fights for 150 miles, burning through hundreds of rounds of ammo, you are already F'd (and that isn't a realistic situation to begin with).   When I had my back-pack 7.5" .300blk with me (which is rare), I only had couple of mags in the bag...it gets too heavy otherwise.    I agree that 5.56 will always be easier to acquire...but it is the expenditure of ammo at such a rate that seems unreal.  

Gun marketed for a fantasy that will never happen. It will sell well.

Gun buyers have this idea in their head that if shit hits the fan (whatever that means to them - nuke, foreign invasion, zombie apocalypse), massive shootouts are going to break out immediately. They’ll be able to effectively participate in said battles with 7.5” 5.56 ARs that they carry with them for this specific reason. Of course, collecting a harem of women along the way home is a tertiary objective.

If Ammo availability was actually the main objective here, a 9mm pcc would make a lot more sense. Much more 9mm rolling around in American cars than 5.56.

7.5 inches work fine. backyard commandos will always complain. i just hat the look of Aeros ribbed for their pleasure handguards

I think backyard commando-ing is deciding that a 7.5" 5.56 (with a birdcage) is the way to go for a fantasy gunfight SHTF scenario.  
A pistol length gas system and 5.56 seem like a bad match for longevity.
The article talks about muzzle blast being a potential issue....yeah...I would think so.  Unless you were always running around with earpro on during SHTF, 7.5" 5.56 seems like a really bad choice, especially in the CQB ranges it is being utilized for.

Shooting at night?  Fugget about it....

Take a deer?  Hope you are not trying to do it quietly (instead of alerting everyone of your location).

And ammo?  Assuming you survived a gunfight...by yourself.....unscathed (after you expended all your ammo), is anyone really thinking they walking into a store and buying more ammo?  If you are walking into a store and buying ammo, you are not really in a SHTF situation where you in roaming gunfights.  

Also.....while better than a sharp stick, if the ammo you are able to get a hold of is the run of the mill XM-193 or green-tips...you are poking holes (again, better than a sharp stick, but that barrel length requires top tier ammo to be somewhat effective anyway).