I’ve seen this suggested elsewhere, and I’m not sure I buy into this logic. He’s using deductions based on a broad set of otherwise well known facts and conclusions that would be available to anyone who thought about it enough, and paid close attention to detail. Nothing in this article is arcane knowledge, or even especially esoteric. It isn’t even exhaustive, as additional imperfections have been identified by commenters on the article and in this very thread.

That it’s collected in this one post might be somewhat useful to someone specifically seeking to produce a counterfeit ID badge made to appear as if it had been created circa mid-1970s, but only to a limited extent as the processes used at the time for such things varied much more widely than they would today.

There’s also the fact that the person who performed this fraud was successful, despite this being reported to eBay by multiple sources before the auction concluded. So there’s not much motivation to expend the additional time and energy drilling down farther on tiny details, if their inaccuracy hasn’t caused them to fail thus far.

If anything, I’d imagine this will be useful to prop designers and miniatures hobbyists, who will exert substantial effort to achieve maximal accuracy just for its own sake.