I wonder whether the economy involved in manufacturing these cartridges, and the printers themselves, wouldn't all but guarantee this costs more than the worlds' poor could ever afford. The article suggests they could buy the cartridges at a local store ... this assumes, first, the existence of a 'local grocery store' and, second, that they have enough money to buy the carts (and, of course, the 0th assumption that there are enough carts to stock the shelves with.)
If they could do that then, presumably, they could already afford whatever else was in the store to begin with, and it would end up being cheaper for the poor who can afford them to just boil the food carts up into soup. I guarantee a synthetic food cartridge is not going to be cheaper than, say, a sack of flour or rice and beans or what have you. And if you're requiring a crowd of people to queue up at the public replicator for their three square meals a day, you've got a recipe for political disaster on your hands.
Now you could couple this with some kind of government sponsored food program, so it's "free" I suppose, But what about regions without any real infrastructure, or stable governance, or even hostile governments?
I'm not dismissing the idea of the printer per se, but I don't see how it solves world hunger. If NASA wants to revolutionize the quality of life in poverty-stricken areas of the world, they should focus on improving global sanitation, water quality, waste disposal, etc.