A more generous interpretation of the article’s claim interprets “BS” to not necessarily mean it is false. For instance, if I were to speak condescendingly on a topic I know nothing at all about, I might (unbeknownst to me) actually say some true things... but most people would consider this BS regardless (both the false and the incidentally true things).

This common-sense interpretation of BS agrees with epistemologists’ definitions of “knowledge”—they invariably define it in such a way that a belief must not only be true, but also true for the right kinds of reasons, to count as knowledge (though there is a lot of disagreement about what those right sorts of reasons are). See for instance the “justified true belief” definition and its critics: https://plato.stanford.edu/entries/knowledge-analysis/