The "everyone" is "everyone with GitHub access" really (there are people on python-committers who are not considered core developers, for instance, so this list isn't used as an indicator of anything). Basically if you're aren't contributing anymore than it isn't as critical to update your info since it's all about permissions to systems that eventually only active team members will have elevated privileges for. But as Brian said, you can ask someone to add your info for you if you want. (And I don't expect us to bother purging python-committers so there's no worry there.)
And I actually can't grant access to repositories; that a PSF infrastructure request to add someone to Python core team on GitHub under the Python org (which I can handle making the request, I just don't click the button that grants privileges).