A disagreement over the PostgreSQL trademark

A disagreement over the PostgreSQL trademark

because of some reasoning like "Well they had to, if they let one little girl dress as Cinderella without an official Disney-branded costume then magically all Pixar movies are Public Domain"

That would be highly unlikely given that trademark law and copyright law are entirely different ball games.

What companies try to avoid are situations where words like “to google” mean “search something on the Internet” rather than “use specifically the Google search engine to search something on the Internet”. It is often a consequence of having been too successful and become what is affectionately called “a household name”. The Hoover, Kleenex, and Xerox companies, among others, also have sad tales to tell about this. By coming down like a ton of bricks on presumptive diluters of its trademarks, the Disney corporation has – in spite of its early and sweeping success in the area – so far managed to avoid a world where the word “disney” is synonymous with “animated feature film”, at the cost of making themselves unpopular with third-party purveyors of Cinderella costumes and their customers. We may not like them for it but it's how their legal departments roll.

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