What does Oracle actually own? Isn't the code committed by all the community members their own property, in other words isn't the code base "contaminated" from the point of view of Oracle?
GPL doesn't apply to trademarks, which are still the property of the company (Sun/now Oracle), just like Firefox is a trademark owned by Mozilla Foundation.
You can fork the code and make your own brand with it, but unless you offer something different, good luck in trying to get JohnDoe to install, say, MariaDB instead of MySQL or YourOffice instead of OpenOffice.
