I think the author is talking about "exoteric" meaning, which is for public consumption, and "esoteric" meaning, which is for the initiated. Even though they say they aren't dogwhistles or shibboleths, these Straussian memes are closely related, as the accusation asserts that there is an "esoteric" meaning to something beneath its "exoteric" face value.

They may be a converse of the Scissor Statement, which has a dual meaning that is irreconcilable between the separate interpreters. (https://news.ycombinator.com/item?id=21190508)