Lucketone likely knows this and was pointing out that "obscurity" is a misleading word to use when talking about systems which all rely on obscurity, in the plain English sense of the word.

We're in a technical forum, discussing a term of art that refers to a very specific bad practice.

Lucketone's argument is essentially saying that the bad practice itself isn't actually a bad practice by equivocating the term of art and the plain language definition.