Hmm it sounds more like a blanketing theory he has. I personally think it's a little wreckless as a professional to tout something as a fact without scientific evidence/information to back up said claims. Do some companies have priorities other than optimal nutrition? I'm sure there are a few bad apples as there are in any form of business, but to group all organic feed together sounds a bit personal, especially with the wide range of options available in the "organic" feed category today. I think overall the best thing any of us can do for our waterfowl is to contact the companies we purchase our feed from and request the full vitamin/mineral amounts instead of basing our decision solely off of the very minimal nutritional analysis that feed companies are required to provide. People tend to overlook the fact that there is a lot more that goes into waterfowl nutrition besides protein, fat, fiber, calcium etc. and it's prudent that waterfowl owners know the amounts required for their birds. Keeping ducks alive is one thing, but maintaining a truly thriving flock is what we all should strive for. Also this isn't directed toward you I'm just saying in general lol
Edit: I will add the one thing that I could see being an issue is that several of the "organic" feeds have whole grains, peas, etc. mixed with pellets where the pellets contain all of the vitamin/mineral nutrition. I could see there being health issues in the flocks that tend to pick out the grains and leave the nutritional pellets, but then again there are many "organic" options that are solely pellets or crumbles with no added grains. It certainly is interesting to think about, but I'll stop myself