One of the things that makes this a bit off is that rice is terrible on the environment and takes a significant amount of water. With GMO grains, that can be worked on, but the other thing is that Rice alone cannot feed a population. You need a protein to go with it, beans, cheese, eggs, meat etc. The other issue to consider is that we make more than enough food, but the problem becomes that of logistics. Then you have the issues of food aid harming local farms Otherwise you math checks out. Now, how do we stop the wars, the border disputes, stamp down on the tribal rivalries, fix the infrastructure issues, roll out electricity, educate the local farmers, build irrigation.... and so on and so on.
I needed a staple grain to use as a standard unit of measurement. Rice is abundant, easy to transport and is common everywhere so its a good standard measurement unit. Now, how do we stop the wars, the border disputes, stamp down on the tribal rivalries, fix the infrastructure issues, roll out electricity, educate the local farmers, build irrigation.... and so on and so on.
I dont think any government is actually interested in doing this for real. Unstable Africa that can be used as a toxic waste dump, and stripped of natural resources is much more desirable for the ruling elite.