That doesn't make it better. We have too much carbon in the atmosphere. We should be growing corn for the sole purpose of pouring it into oil wells and coal shafts.
It is certainly better than adding more greenhouse gasses, which is what fossil fuels do. Burning, for example, wood obviously does not reduce greenhouse gasses (nor does anyone claim that), but from a greenhouse gas standpoint it is clearly way better than digging up even more CO2. There are certainly other very important factors to consider, but if the discussion is global warming than you can give me a tree farm over a coal mine any day.
Dumping corn down mineshafts seems like it would be pissing in the ocean. Maybe instead of pissing in the ocean we should be experimenting with dumping fertilizers and nutrients into the ocean to trigger algae blooms. If that works as the theories say it should, and is seen to have acceptable consequences, that is something that we could actually do at scale (and without further subsidization of corn...).
We're not entirely clear on how that works, and our best estimates are that it takes on the order of hundreds of thousands of years and requires quite a bit of pressure. The proposal above would basically be a deep landfill, and generally what will come from landfills in our lifetime is methane, CO2, dirty water, and a lot of garbage sitting around.
Dumping corn down mineshafts seems like it would be pissing in the ocean. Maybe instead of pissing in the ocean we should be experimenting with dumping fertilizers and nutrients into the ocean to trigger algae blooms. If that works as the theories say it should, and is seen to have acceptable consequences, that is something that we could actually do at scale (and without further subsidization of corn...).