alt Hacker News> The term is a compound word joining goy, a Hebrew and Yiddish word for a non-Jew or gentile,[4][3] and slop, meaning food waste or refuse of low quality
So you're telling me that a word which has "slop" in its origins is itself the origin of "slop"?
This must be the first case of circular etymology!
There are a couple of other cases. Dog was once (1845, UK) slang for sausage, due to fears of dog meat. Then a hot sausage was a hot dog, and then hot dog was a sausage, and finally just dog was slang for a sausage again, with the sinister implication removed. I also found pepper, from Latin (from Sanskrit?), leading to pep, the thing a pepper does to you, leading back to pepper (a kind of pre-game warm-up in baseball designed to give players pep).
You might object that those are really back-and-forth, but so is the claim being made here about slop. (I kind of doubt the claim though.)