How would this affect you if you are using Github as a OAuth provider? Does Github mention under what conditions they are going to take away someone's username? No code? No OAuth? No activity?
Most corps are looking at GH EMU, which means you bring the username/email address, and that a public GH username is not possible. This also prevents the creation of public repositories.
https://docs.github.com/en/enterprise-cloud@latest/admin/ide...
The people they care about don't use GitHub oauth, but instead use their own private idp like Okta.