I think it's been done to death, and we all agree, that a 1,000 Kg overweight incident is neither here nor there in the "ability of the aircraft to fly" scheme of things.
What is the issue, IMHO, is the attempt to sweep the incident under the carpet.
If the guys unloading the aircraft had of filed the appropriate report at the time, the incident could of been quickly investigated, the cause of the error found and corrected, whether it be a system error or human error, lessons would of been learnt and the world would of continued on its merry journey around the sun.
If we all agree that there is no "ability to fly" issues with the Bus being 1,000Kg overweight, yet if the same aircraft was 40,000Kg overweight it would have, to be diplomatic, severe performance issues.
So somewhere between 1,000 Kg and 40,000 Kg there is a "billowing column of smoke just past the end of the runway" line at XX,000 Kg.
The issue is, IMHO, that a system that lets 1,000 Kg through today could let that XX,000 kg through tomorrow.
When an error (letting the 1,000 Kg through today) is detected, it behoves one and all, every person involved, every department involved, as well as the company to loudly say "We stuffed up", to give thanks nothing serious happened, to learn the lessons and apply the remedial action to lessen the chance of the same thing happening again. Tomorrow it might not be 1,000 Kg.....It might be XX,000 - 1 Kg.............
OR it might be XX,000 +1 Kg.
ST