While it is entirely possible that Gates truely believes in the ‘soylent green’, synthetic foods model, that is not the only explanation.
As the largest land owner in the world, he may be aware that his extensive acres can only be worked in the way he describes with ample supplies of petroleum power and chemical fertilizers and pesticides/herbicides. Yet this is precisely what the “Progressive” model of the future rejects. We are supposed to replace gas and diesel power with electric power generated by “clean, natural” means. but there is no way wind and solar power can generate enough electricity to run a large, modern factory farm.
On the other hand, large farms without petroleum products would employ large numbers of human laborers. And Artificial Inteligence, which Gates’s computer businesses pioneered, has and will put many persons out of work. So, they will be available to be serfs on Gates’s plantations. Looks like he is planning to bring back feudalism.