I have user account on my personal Google Workspace domain that is used purely for superuser access (my day-to-day account doesn't have special access).

I recently had to log into it for the first time in a few years to make a config change to the domain, and it wouldn't let me in because the 2FA code wasn't working, and a recovery code wasn't sufficient to enable privileged access. I had to reach out to Google Workspace support to regain admin access to my domain.

Thankfully, they were able to do so (although it took a few days and I had prove ownership of it).

So there's an example of a situation where an account that's not logged into for a long time doesn't mean that it's forgotten or unused.