Absolutely. Big if.
Even if O’Neil is right, there’s not a ton it changes. Mainly, I think it challenges the (already shaky) notion that the flavorful pomegranate syrups a lot of us are using today are somehow “more correct” than the vulgar commercial grenadines. (We can still have our preferences, of course.)
For the pre-Prohibition cocktails, the question becomes whether we’re missing something extraordinary, taste-wise? Is a Jack Rose made with Clove-Pinks something as (or more) compelling than a Jack Rose made with pomegranate syrup? To take a quasi-parallel example rife with its own semantic confusions, we had no idea the Gin Cocktail was one of the great drinks—as opposed to a terrible one that was inexplicably in the books—until we got sorted that the “gin” in the Gin Cocktail was actually genever.