From what I can gather, Cuil was a sort of search engine that created summaries of pages using some algorithm. This algorithm often spliced together strange sentences without context. If you look at the whole thread, it seems that the person before the linked comment makes an analogy between Reddit's algorithm to determine thumbnails for a given link, and Cuil's algorithm to generate summaries.

Then, the user that was linked to, goes on to describe a technique to use the term "Cuil" as a unit of measurement, for how disjointed something is from something else.