Depends on which AK he was using, honestly. Short or long barrel, what sights, etc. Some AKs I’ve seen are pretty damn miserable even at close range.
He should get a bit of a pass on it, honestly. The other thing is that we don’t know that he didn’t hit any of the others, if his field of fire was obstructed (remember, there were customers in the store - bad idea to accidentally shoot them) or really much of anything else of how it unfolded.
If this is the same store I remember being in the news some years ago for a prior robbery, he’ll have video and it should be released soon.
The ranges here can't be more than 20 yards. Let's say AK accuracy is a miserable 4 MOA (4" at 100 yards). That's 4/5" at 20 yards. That means a dispersal pattern of less than a inch for shots fire.
Plenty accurate for CQB.