is your repositories updated?
in my system, python-dateutil is installed and not marked for removal!
is marked in RIGO or by commands? In Entropy or in Portage?
because sabayon (as gentoo) mark the package for removal or downgrade, if this necessary for install an new package and carry this automatically.
After the other package installed, if the system uses the "removed" package, it will be auto reinstalled!
The only packages that i see truly "marked for removal" are in Portage, bu are marked for removal in the repositories, not in your installed system.
If a package will be removed from the repo, it will no more updated or upgraded, then,
if you or your system uses the package, it should be not uninstalled.
Example, Portato nom more exists in Entropy,neither in Portage,
but i mantained Portato in my system,since i like portato and use It.
If you remove an old package because it will be deprecated in the repos,
but you like the package, you cannot more re-install it.
ALBERTO FEDERMAN NETO
Favorite Distros: Sabayon, Gentoo, Mageia and OpenSUSE