The vagueness is real in the description but he’s a good guy and will communicate with you.
I just assume argon capped bottles. No real wizardry.
The 90%+ and ND + argon/other gas capped = primo for the price converted product
Then again maybe it’s been left out to oxidize and has been proven it won’t. Great question.
The color changing is the least favored oxidation sign. I imagine they’ve figured out the color control. If it’s more seriously worked than just capping liter bottles with argon.