Having inactive core developers temporarily lose their commit bit with an early reminder and the ability to reclaim it following some review sounds good to me. I think this is especially prudent for a project like CPython where reviews are not mandatory, so a core developer account is already quite able to do harm on its own.
Speaking on the administrative side: I suspect adding this process might handle some tough squishy parts around moving folks to emeritus without someone from the core team needing to both decide and be personally responsible for revoking their access. There are a lot of feels involved in moving on from a project and active commit access doesn’t need to be tied to celebrating past contributions.