First of all, the direct causal relationship between very high calorie diets and Non-Alcoholic Fatty Liver Disease (NAFLD) is irrefutable, and if you got your daily protein requirements from Jiffy then you'd consume 2715 calories with almost no other nutrition, so I'm assuming you don't need a source on that well known fact but I'm going to go digging for statistics on peanut butter anyways.

https://www.mdpi.com/2072-6643/11/11/2744

"Effects of Some Food Components on Non-Alcoholic Fatty Liver Disease Severity: Results from a Cross-Sectional Study"

"Moreover, in the group of protective foods, in addition to winter ice-cream, chickpeas were associated with a 43% lower risk of severe NAFLD per g/day intake. Conversely for “promoting foods” in addition to industrially produced Aged cheeses, Sweet Products Milk-Based Food Group (without winter ice-cream), the Fats group comprising: seed oil, peanut oil, butter, sunflower oil, corn oil, margarine, olive oil, extra virgin olive oil, soy oil, were associated with a 12% higher risk of severe NAFLD per g/day intake."

https://link.springer.com/article/10.1007/s00394-017-1492-1

"Chronic consumption of fructose in combination with trans fatty acids but not with saturated fatty acids induces nonalcoholic steatohepatitis with fibrosis in rats"

"Fructose in combination with TFA caused NASH with fibrosis by inducing oxidative stress and inflammation, whereas, fructose in combination with SFA caused simple steatosis, suggesting that the type of fatty acid is more important for the progression of NAFLD."

NOTE: This study is on rodents not humans

2nd NOTE: The Peanut Oil in this study actually led to less bad results than the other high caloric diets tested on mice but still resulted in what they called "steatosis" which isn't clarified as staetotic liver disease or as some other form of fat retention so it's slightly ambiguous but the context points to liver disease.

https://pmc.ncbi.nlm.nih.gov/articles/PMC10136128/

"The Effect of Bioactive Aliment Compounds and Micronutrients on Non-Alcoholic Fatty Liver Disease"

"The recommended daily dose of peanut butter is 2 tablespoons of natural peanut butter (about 28 g). This dose is equivalent to 160–200 calories, it is therefore true that this is a spread high in fat and calories, but at the same time, eating peanut butter will provide a long-lasting feeling of satiety, thus preventing the phenomenon of excessive snacking [69]. When you add snacks, blood sugar levels rise and remain high for a long time, which is not a desirable situation in the prevention of diabetes and NAFLD."

NOTE: This one is EXTREMELY pro-peanut butter and still acknowledges it is a risk if you consume the amount suggested in the satire.