Even if you ignore the subthread of whether or not the OSI coined the term "open source" or if it was previously used, I think it's valid to standardize terms.

Even if you ignore the subthread of whether or not the OSI coined the term "open source" or if it was previously used, I think it's valid to standardize terms. Imagine everyone had browsers with slightly different ideas of what HTML was, and then the W3C comes along and says "we're going to standardize on HTML meaning this", and then, 20 years later, I think it's valid to say "this isn't valid HTML" to mean "this HTML doesn't conform to the W3C's standard". Or, to pick a different example, just because the word "planet" has been used for thousands of years with varying definitions doesn't mean that it's wrong for me to say "Pluto isn't a planet" rather than "Pluto isn't a planet™ as defined by the IAU". I think if a word is previously vague and unclear, and then a standards body steps in and defines the edge cases, and everyone uses their definition of the word for decades, I think that's good enough to use that definition for everyone going forward. You might have had an argument 20 years ago when the word was newly standardized, but it's too late now; just pick a new word like "source available".