Well, I'm certainly no expert on mold, but can you not simply put on a pair of rubber gloves and clean the exposed wood studs with bleach to kill the mold.
Also, in Europe, borates are a common treatment to prevent wood rot, and are the most popular wood rot preventative amongst log home owners in North America because borates are the only wood preservative that penetrates throughout the entire cross section of the wood. You can Google "Boracol" or "Sasco" or "Sansin" to find the products (like Borocol 20-2BD and 40-2BD, or something like that), and the companies in Canada that market borates. Sasco is in Nova Scotia and Sansin is a subsidiary of theirs in Ontario. Borates are highly effective against wood eating fungii, like the wood rot fungus, but my understanding is that they're also effective against all kinds of mold and fungii, not just wood rot. The people at Sasco could confirm that. Surprisingly, borates are almost harmless against mammals like people and pets. We can just about eat borates and not get an upset stomach. Borates and the Borax you might use to clean your laundry are chemically related. My understanding is that Borax is Boric Acid, whereas the borates used in Borocol and solid Impel and Cobra rods is something called "disodium octoborate", or something like that.
The problem with Borates is that they're soluble in water, so another flood would dissolve and wash away the borates up to the level the water rises to in any future flood, but that's not much of a problem since you'll undoubtedly be removing the drywall and exposing the studs up to that elevation to replace the damaged drywall anyhow.
Also, my understanding is that copper and zinc napthelene are effective at protecting wood from wood eating fungii because both copper and zinc are natural biocides, copper being the more effective of the two. If copper is a natural biocide against wood rot fungii, it seems to me that it might also be effective against other types of mold and fungii as well. So, I'm wondering about using 3 and 10 inch paint roller sleeves to paint the studs and back of the new drywall, respectively, with copper naphthalene end cut preservative, or Borocol, to kill any mold spores before they start to grow.
As I say, I'm no expert on mold, and there are much more knowledgeable people than I in here on that subject, so I'd wait for their opinions on the matter.