> Why do you presume he uses git, though? He might, but he may as well use cvs or sccs or just a set of dated folders named “…-final2(7)”.

He might also still be using SunOS or HP/UX or maybe even 386BSD.

But is that likely? Not being pwned/hacked for 25+ years while still using the same old OS? On the internet that changed quite a bit since HTTP/0.9? While using the GitHub website with TLS and HTML5 and JS requirements to register an account which doesn't run in such an outdated browser?

I think your assumptions about statistical likeliness are a bit off.