It does not sound like cover up to me. It was simply the explanation of what happened. I didn't get any hint that the said "staffer" will be fired or otherwise

It does not sound like cover up to me. It was simply the explanation of what happened. I didn't get any hint that the said "staffer" will be fired or otherwise punished. Is there a problem with the system that did not have enough safeguards to let this happen. For sure, but then no system is perfect. This glitch does not happen every day. From memory, I remember a NASDAQ glitch at Facebook's IPO. Let's say there are 2 or 3 glitches like that for major exchanges in one decade. How can you design a system that prevents bugs that show up once a decade?