Doesn't the GPL rely on copyrightability of APIs, in that it claims even code linking to a GPL library is subject to the GPL? That's one reason this might be surprising; a finding against API copyrightability might be taken as undermining the GPL.
I don't think so but I'm not an expert. The ruling in this case would be that no own could implement the same API without violating the copyright on the GPL code. For example you couldn't create a GPL free glib etc.
I would be willing to bet that if that ruling would cause vastly more issues than it solves for the open source community.
