Poor people don’t have that much land, nor is it good land; rich people own the good farmlands. People cannot eat poor-quality grass & weeds; however, the guinea pigs quickly convert grass to meat protein and the people can eat the guinea pigs roasted or stewed, and with the few plants they can find or raise, have a decent diet.
Surplus guinea pigs can be traded or sold as meat for income, which gives the poor a way to survive and even flourish; if they get money for the meat, then they can afford a pair of cheap shoes or a shirt.
This is why these large guinea-pigs are called “micro-livestock.” You don’t need much land or space to raise enough grass to sustain a flock of 20 or 25 guinea-pigs in a shed for food and trade. I have lived and worked in third-world countries, and know how hard it is for the poor to get decent nutrition.
You are probably used to having more than one meal (and no snacks) a day; these people are lucky to get that. You should not let your prejudice against meat-eating blind you to the fact that meat protein is necessary to keep many people alive in desperately poor countries. Remember that Guinea pigs originated millenea ago in Peru as food animals; they only became pets in Europe in the early 19th century. Remember, in time of war and famine, even people sentimental about their pets eastern europe in WW I & II got so hungry they ate their dogs and cats; they don’t put this in the history books because it upsets school- children. In the seige of Leningrad, (an other less-known places) once all the pets and zoo animals were eaten, many survived by canablizing their dead relatives. (Look it up.)