Earlier quoted context omitted.
To anyone at GitHub reading this, this thread has motivated me to move the rest of my projects to a self-hosted solution. Putting all my eggs in GitHub's basket is evidently too much risk for me to bear.
Just back up the data somewhere else. No matter what you use, there's a possibility that your stuff will just vanish one day. Your own hard drives could die, your building could burn to the ground. Don't put your data into something that you can't get it back out of later. Off site backups are like sysadmin 101. You even need to back up your cloud infrastructure, it's not unheard of for any of the cloud providers to…
But if GitHub bans you, good luck with that. They're not just deleting your data; they are removing you from your own community, because they control its environment.
Edit: And the domain name system, unlike services like GitHub, actually has processes and mechanisms in place for recovering access and filing disputes.