Howard has spoken about this on the radio program several times. An advertiser and supplier of corn gluten meal used to claim it was organic, but they let Howard know that they could no longer make that claim because of the mingling of pollen and such.
Corn is still going to be a better ingredient in your yard than chemical products, so if you are torn by the decision, go with the corn products. Howard has made some substitutions in his routine, so he is using less corn. See the entry in the Library of Organic Information about corn gluten meal
If you don't have a chance to listen to the radio program you might want to visit the part of the website with links to the podcasts and listen to past programs. He says a lot more on the programs than is written in the forums.