I am not quite sure why we are even considering Github. So I would not even be considering it as a Free Software Organization
My primary vote would be a self hosted community edition of GitLab.
Also please note that there are various amamzing alternatives too, which I would gladly consider
Pagure is a project by Fedora which they use to host their code. Once of my friends has been selected for GSoC this year and he is contributing to pagure private repos and pagure pages (just like gitlab pages). With these two features, I see pagure as a right tool to proceed with, since pagure pages could also help us host static websites for the projects we use.
PS : Community Edition of GitLab doesnot provide gitlab pages and other stuff. All that it provides is public and private repo hosting along with a wiki and issues.
Gogs : Gogs is basically a git web hosting written in go. It is a free software and also a decent one.
Gitorious : Even though gitlab acquired gitiorious , the code is still a GPL’d and we could happily host things.
GNU uses something called Savanah. Which is also pretty amazing.
With so many options, the whole question of Github to me seems a joke. I know you would immediately say a lot of people are there and things, but it dosent matter. What matters is “Is the tool free”.
But just for the public presense, as @welkin pointed out, we could just have a github group and use it only as a public mirror and not for coding.
So my take would be, to use gitlab.com presently, and with GSoC starting off, we should private repo’s and pagure pages up and running possibly within 3-4 months. Once done, we should be able to host our own pagure and run with it. I would still not advise Gitlab Community Edition
Read up on this : https://libreboot.org/gitlab/