Well he's wrong but only in the strictest semantical sense of the word.(posted 8171 days ago)If I were a Zone System purist, which I am sometimes but not all of the time, I would be remiss not to remind you that there are a lot of terms bandied about in photography that have no real quantitative meaning or relevence - words like ISO film speed.
The actual ISO standard has very little to do with photoraphy and more to do with sensitometry - the study of the affects of light energy on photo-sensitive materials. A good introduction if you are so inclined is Todd and Zakia's "Photographic Sensitometry". It explains where the standard comes from. I could reprint it here but it goes on for pages and we'd all have to hold our heads together so they don't blow up.
Exposure Index is a more practical - Zone System - term which is your own personal speed for a particular film / developer combination based on your practices, the water quality in your darkroom, the way you agitate, and a bazillion other variables.
But in practical terms, when you arrive at a film speed that works fine for you regardless of how you got there (trail and error or densitometer) it's your EI and you should stick with it as long as it works.
And don't worry about the terminology or whether or not Kodak is lying to us.