Christ on a crutch. It was technical, obviously. First of all, the trades that created the August 1 mess were ALL in exchange listed stocks. NYSE stocks, to be precise. Have you forgotten that?
Second, they were not properly marked as short sales because they weren't supposed to happen in the first place.
These days, the SEC is cracking down even on unintended mistakes. I could go on about Rule 105 violations, but it would be pointless.