Interesting, I wonder how they could make a case for that. Do you have any references? I have heard of developers independently reimplementing GPLed code, being careful not to read a single line of the original code to avoid any chance of their work being seen as a derivative work (this is quite similar to what I did in this case btw).
It used to say this on the MySQL web site. IIRC this is back in the 3.x days so quite some time ago now.
At the time it seemed like a ridiculous claim that no one took seriously. In the days of the 'structure, sequence and organization' of an API being copyrightable, I'm no longer so sure...
