I can only suppose that monitoring position limits is considered a vulgar Anglo-Saxon banking practice and therefore much disdained in La Belle France!
As I recall the original story, he had previously worked in some position in the company which gave him knowledge of a 'back-door' into the trading system. That knowledge let him completely bypass the normal system safeguards. He apparently also had a way to cover his tracks. This went on for quite some time before it was detected.