The Journal feeds are designed such that the owner of a journal can decide to have a feed for his/her journal or not. So that isn't something that belongs into the global Content Syndication panel.
What would make sense is a feed that lists the new entries from all (public) journals - and that could then go in the Content Syndiaction panel.
Go to
http://project.geeklog.net/projects/journal/ and submit it as a feature request ...
bye, Dirk