Even that it sounds strange in social software, in some cases (e.g. short term employed person working in a project) line of business requests that users even can access public or moderated communities is case that they are a named member.
Please introduce a role/user restriction like "only named community access" for certain users in a next release.
This sound to be very similar to an external users. Still there is one major difference. This kind of users are internal, can create communities and do all other kinds of work in IBM Connections. As well the role could be changed as soon as the employment is switched to a long term relationship. Finally this user type has a full license, since she/he belongs to the same organization. This is quite different to a free of charge external user.