That is a common phrase in ergonomics. I myself don't speak any Latin apart from a handful of phrases, like et al, et ceterea, pecunia non olet... - the usual stuff that I think most people have been exposed to. And "ceteris paribus" is THE phrase in economics. It of course applies to all models, but in that field it's actually being used in everyday speech, and always and immediately (when starting to study anything "economics"). I'm not even an economics person, only learned a little bit of it on the side (didn't find it interesting enough).
So it is NOT a stretch at all to assume that someone who wants to debunk a statement made on the basis of the boring standard subject of economics, the supply and demand relationship, has heard about it! If not, it would be even worse for his statement.
