So the broader question is: Is the Plone foundation also in charge for the buildout GitHub organization? If not who is taking care of it and governs it?
The project is not under the hood of the Plone Foundation. Nor it was - AFAIK - under the Zope Foundation. That said it is not necessary to sign a contributor agreement.
People wise Godfroid Chapelle @gotcha is the active maintainer of the project, so he, Jim Fulton as original author and maybe Tres Seaver should know more details.