Podcast 39 with Gordon Strong

I found the latest podcast #39 with Gordon Strong very interesting. Especially his method of mashing the grains that need to be mashed and the adding the specially malts that don't need mashing during the vorlauf. I understand how this can simplify brewing chemistry, but what I don't understand is why the pH offset you get from the specialty malts is taken out of the equation just because they are added at the very end of mashing.

Can anyone clarify?

With respect to enzymes, the pH only matters when they are active. If you're adding grain without enzymatic potential, after conversion, then their pH contribution is a moot point.