I'm pretty sure that this is the correct procedure for creating a renamed spin:
Download the generic-logos and generic-release or fedora-logos and fedora-release .src.rpms. Rename them and change them to your liking. Rebuild them. (Whether you start with generic- or fedora- depends on if you intend to abide by the Fedora trademark restrictions.)
Create a new yum repo for your spin. Put the new dowdlelinux-logos and dowdlelinux-release src.rpm and noarch.rpm files in the repo.
Add the repo in the spin kickstart files so that you're loading packages both from Fedora and from your repo. Also add:
-generic-release -generic-logos -fedora-release -fedora-logos +dowdlelinux-release +dowdlelinux-logos
Then build your spin and it should just work without any ugly stuff in the %post section. Also, this will give you the opportunity to change the Plymouth theme, desktop program menu button and so on.
/Alexander