That's not always true, they recommend if aging longer than 6 months than additional sulphite should be added. They fail to specify if aging in bottle or bulk. I don't see the difference as Sulphites bind to the oxygen and bacteria over time and cancel each other out to some extent. So how is wine aging in the bottle compared to a carboy any different? If anything wine ages faster in the bottle due to temperature swings and such, it also exposes the wine to more oxygen than a fully topped carboy woulds. I would think the additional Sulphites would be needed for bottle aging.
It seems some of the sulphite that didn't bind when you serve the wine if you decant or aerate will disapate anyways. I have always been adding the additional 1/4tsp right before bottling. I rinse my bottles with sulphites also prior to bottling. Typically though if I open a bottle the next day after bottling it has a bit of the aroma of Sulphites, however I think this is because I rinse the bottles with the sulphites, the aroma is not present in the weeks or months of bottle aging. I guess I just chaulk this up to the same as bottle shock, typically most bottles need a good month after filtering and bottling and I try not to open them.