But the main issue is that they didn’t create the automation, not that they couldn’t. You can fully manage Github repo with the API (for example using Ansible, and I know that Microsoft did exactly that, and had a internal portal to people could connect their Github ID to Microsoft Internal AD, and it would add you to the right group, give right access on projects (it was a few years before they acquired the company, so now, I can’t find it 
). But Red Hat do exactly that, you are removed from specific groups on the Openshift org as soon as your account is closed in our LDAP (where people indicate their github account).
So while there is a argument for the lack of automation on a lot of SaaS, I think this doesn’t apply to Github in that case.
Now in practice, I know no one who do that (not even me, who in the past automated phpbb configuration in Puppet, or suggested we automate matrix room creation using ansible to the Ansible folks).
I suspect that if Void Linux folks were ok with non automation of Github, they would also have not automated a self hosted gitlab.