I'll be curious to see where this discussion goes after people listen to what Joe has to say on today's podcast.
I gave it a listen. It's interesting to get his take on Brewtan B, and while most of what he said is technically correct, it's incorrect to conclude that Brewtan B prevents oxygen from reacting in the mash/boil altogether. I actually noticed that Joe hedged a bit on this - he said oxygen wouldn't react in the same way it normally would. He didn't say it wouldn't react at all.
Oxygen has more than one pathway to react with stuff in the mash. The Fenton reaction is only one of these pathways. Another set of major oxidative pathways are through naturally occurring enzymes found in the malt, such as lipoxygenase and polyphenol oxidase. I think polyphenol oxidase is the real bogeyman here, because we hypothesize that the simple, low molecular weight malt phenols are the main source of the fresh malt "it" flavor, and polyphenol oxidase is specifically made for catalyzing the oxidation of those phenols.
To use an analogy:
Using Brewtan B in oxygen-saturated water and expecting zero oxidation to take place is like mashing at 160 F and expecting no starch conversion to take place because you've denatured beta amylase at that temperature. It doesn't work, because you've overlooked the fact that alpha amylase is still active at 160 F and provides another pathway for the starch to convert.
This is a side-by-side picture of wort produced with a normal process (on the left) and wort made with the low-oxygen process (on the right). The color difference is indicative of the fact that the polyphenol oxidase enzyme has been inhibited. When polyphenol oxidase (which is the same type of enzyme that turns sliced apples or avocados brown when exposed to air) oxidizes the malt phenols into quinones, they polymerize to form reddish-brown polyphenols. The fresh malt flavors of the phenols disappear, and are replaced by a bitter malt flavor (George Fix called this "herbstoffe").
If Brewtan B doesn't make the wort several shades lighter (like the picture above), then it's not blocking all oxidative reactions in the mash.
I think that Brewtan B could absolutely be a useful tool, and i see it helping more post-fermentation because the Fenton reaction is also a big oxidative pathway in finished beer. So it could definitely help with shelf stability there - but I don't see how it can possibly be a magic bullet all by itself. Note that other commonly used additives like gelatin and Irish moss can also have metal chelating properties.