It terrifies me to have a patent on the only crop that can grow in a country.

Food is a necessity

What happens if the seller decides to quadruple the price overnight ? (à la OPEC but for crops)

If some country does 'sanctions' ? (like Russia or the USA when they can't just declare a war to a place)

or if the economy collapses and imports are expensive ? (imagine Venezuela, but the country is also not able to buy crops that work)

these crops sellers will own the Kenyans.

I wouldn't buy the crops if patents were enforced.

it feels like some SF novel (or the Washington Consensus, yet again)

Back in the days, China forced foreign companies to work with domestic companies to sell in China. And at least, they are independent on some technologies now.

You don't need patent enforcement for hybrid crops, which is pretty much every seed other than soybeans which is an heirloom crop. Corn has major hybrid vigor, so only a totally ignorant farmer would try to replant harvested corn. Corn seeds are made by crossing two heirloom corn varieties at a seed farm, e.g. Southern Dent is crossed with Northern Flint (both are about 5 feet tall and make small ears), to make hybrid corn which grows about 8 feet tall and has massive ears. When you sell seeds, you don't get access to the heirloom plants needed to make the seed. No need for patents.

With soybeans however, they breed true as heirlooms. The GMO beans were sold with the promise that farmers don't use the crop as seeds. Since everything other than soybeans are hybrids, the issue is largely moot.