That's not an option any more. GitHub used to offer this, but as of about 12 months ago, the policy changed and they will not release a name that is inactive regardless of how long it has been inactive.
Using recent activity as a metric seems like it would age finished projects out of the github platform. Active projects that have switched version control several times in their history might refer to previous versions on github without github itself being aware of the connection.
At the free level I could see unmodified forks and anything marked private disappearing over time, then culling empty accounts. If I created an account, forked a project, and then left, how many months would need to pass before I'd be surprised that my account hadn't been recycled without my active consent?
At the free level I could see unmodified forks and anything marked private disappearing over time, then culling empty accounts. If I created an account, forked a project, and then left, how many months would need to pass before I'd be surprised that my account hadn't been recycled without my active consent?