If readers refer to the article, the reason for the easter egg was because the textile execs hired to manage game development treated the idea of crediting developers as absurd, and so the developers inserted evidence of their work into the games as easter eggs, literal hidden paths. While it was not direct copyright enforcement, it was leaving a "makers mark" on the product, which has precedents in other fields such as map making. Or, I'm probably just too dumb to tell the difference and this insight was both incisive and deeply edifying.
