> his qualification

Are you referring to "every" cocktail meaning "every IBA" cocktail? No complaints there, that's just headline writing.

But there's a reason I called out the Vesper -- it's on the list! And I'd argue it's the cocktail on the list that, most obviously, no one can make today. It's not a cocktail that allows creativity or substitution in its ingredients -- it's specifically a showcase of Kina Lillet -- and its key ingredient isn't available today. The correct response to someone ordering a Vesper should be "I can't make you that, but maybe you'd like a <something related>." (Or, honestly, "meh, we can do better than that" -- it's a mediocre cocktail at best, but that's not the point.)