The social contract doesn't say they can't use software that isn't GPL'd. It says contributions to Gentoo should be GPL'd. The developers don't have the same contract as Debian.
If linux gaming will ever take off, it will need to be commercial and not GPL. There is no money in GPL for game developers.
So nvidia closed their glx driver? Does that mean I shouldn't use it for my Linux gaming box? I have to buy most of the games anyway, so obviously I don't care about everything I use being GPL'd.
And on that note: Gentoo rocks. It is the fastest distro out there by far.