Corks are ready to go from manufacturer. Mine come with a warning they are gassed with SO2. Smaller quantities (<500 from my supplier) have been repackaged. Most suppliers who repackage probably do it under sanitary conditions. I doubt they gas’s the package as the manufacturer did. But, who knows? I ask when they were repackaged.
Keeping corks protected and the moisture content correct is what we as amateur smaller lot buyers must do to help protect our corks when we purchase more than we need at one time. SO2 in a bucket with some distilled water on a sponge for moisture will help. Still, the longer you store them the greater the risk they will fail. The best bet is to buy what you need when you need it or share a larger order with others. The recommended methods of storing, rehydrating and trying to kill off bad stuff may work, it would not be my best practice. I would not risk a closure ruining a wine I’ve invested two years crafting.
FWIW: There is a lot of discussion about how to make thing work or will they. This post is an example. I make about 200L of wine each year and most of the supplies I use have been repackaged (even some yeasts). Grapes (the whole process) are a big investment and, because I don’t want to add to my risk of spoilage, I only use reputable suppliers with inventory turns and buy fresh yearly. Supplies are the cheapest input. Why risk any input other than my skills?