Hi there! I’m the commenter you mentioned, u/RiceEatingSavage, that’s me. My comment… isn’t deleted, so I'm not sure which one you’re referring to?

Still, thanks for posting your question! This is the exact topic that got me into my main research interest as a whole, so I’m quite excited to get a chance to discuss it here.

First, let’s begin with the history of rice and the South. In Chapter 129 of the Shiji 史記, Sima Qian 司馬遷 describes some of the ethnic stereotypes of southerners (Chu-Yue people). He writes in the first century BCE.

... in the territories of Chu and Yue, land was broad and the population sparse. For their food they had rice, and for their soup they had fish. Some of them tilled with fire and weeded with water, and the fruit and shellfish were sufficient without need to purchase them in markets. The land is by nature abundant with things to eat, and there is no danger of famine or death. For this reason, even those who are weak or ill can manage to survive, there is no occasion to store up goods, and many of the people remain poor.Thus, south of the Yangzi and the Huai, there are no people cold or hungry, but there are also no families with as much as a thousand catties of gold.

Meanwhile, in the Hou Han Shu 後漢書, compiled in the 5th century CE, Fan Ye 范曄 makes similar comments about Southerners in the Chronicle of Geography.

Watered by the Yangtze and the Han, Chu is a land of lakes and rivers, of well-forested mountains and of the wide lowlands of Jiangnan, where burning and flooding make the labors of ploughing and hoeing superfluous. The people live on fish and rice. Hunting, fishing and wood-gathering are their principal activities. Because there is always enough to eat, they are a lazy and improvident folk, laying up no stores for the future, so confident are they that the supply of food and drink will always be replenished. They have no fear of cold and hunger; on the other hand, there are no rich households among them.

Sima Qian, besides his (relatively common) spiritual tendencies and vendetta against a certain emperor, can generally be taken as an impartial representative of his time (the Former Han). And Fan Ye, who was born in the Southern state of Wu, has no real motive to demonize his own countrymen when transmitting history from the Later Han.

While single texts are not enough to extrapolate a whole cultural shift in attitudes, these passages at least give us some insight into the variety of views from which ethnic views of rice during the Northern and Southern Dynasties would grow. Some viewed the South as lazy and unambitious due to rice. Others regarded it as a land of plenty. But the general stereotype was one of abundance and satiation without wealth-building.

cont. in next comment