Except that you can't copyright a language specification - just the implementation of it. And even if you could, copyright law wouldn't prevent you from re-implementing it!
I mean, look at it this way - GNU is almost completely compatible with Unix, but it was rebuilt from the ground up. Even if AT&T hadn't given out the license for free, you'd have a hard time convincing me that GNU breaks some sort of copyright - the entire damn codebase was rewritten from the ground up. The design of the operating system may be the same, but copyrighting that is as ridiculous as patenting a geometric shape.
