Making Published Content Only Available to Portal Members
The Plone workflow associated with a Plone content type manages Zope security settings for all objects of that type, overriding the Zope security settings defined on the objects themselves. If one wants to restrict access to Plone content, e.g. to only portal portal members, one must modify the corresponding workflow, by change the security settings in the workflow's states or by adding additional states with the desired security settings.