PD is suitable for ANY use. Including the simple process of slapping on a license of your choice. Once you co-mingle PD and GPL'ed code. It becomes pretty clear which is which. The whole concept of GPL'ing a database sounds broken enough that a court would end up very, very, confused.
Confused courts do bad things just to make a point to the stupid.
Sounds like we need a GDPL, General Database Pubic License, real soon now. For the latter, which I think this discussion is about, I don't see any problem. Also note that Stallman has spoken against copyrights on collections of data before. The following comments are owned by whoever posted them. All trademarks and copyrights on this page are owned by their respective companies.