Have you ever shot an AK?
Sure, an expert marksman wouldn't choose one for really long shots, like 600 yards or more.
They are very accurate out to 200 or so, which is more than enough for this purpose.
As matter of fact I have. Several, as well as many other rifle calibers including .223 ARs 308s, 260, 6.5 7MM, etc. However, at my current stage in life I now prefer bolt guns that do sub minute of angle at 100 yards. I have a few that can routinely do same hole at 100 yards and an inch to an inch and a half at 200. I am no marksman but I enjoy prairie dog shooting and no longer take a shot less than 300 yards.
In my personal experience, off all the semi auto rifles I have shot over the years the 7.62X39 AKs seemed to be the least accurate. I liked the SKS's better. If the perps were really into precision shooting they would not have used and AK. More likely they were ragheads on a budget or home grown idiots out to create an event, or perhaps someone with an agenda hoping to stir up the assault rifle hysteria again.