My initial charitable reading -- as someone who sometimes dabbles in decaf -- is that decaffeination has the bad side effect of stripping flavors, and likely many of the other biologically active chemicals. I can see from their further posts that they were more interested in unscientific fear mongering instead.

That said, I do think there is some truth that decaf is lacking (including via supercritical CO2) and I wonder how long until we could have a product like genetically engineered coffee plants that produce everything except caffeine. I'd like that, though I can immediately see an issue with growing a plant without its natural pesticide.