Could we substitute this line with:
Your default user picture is viewable throughout the LiveJournal site, and unlike individual journal entries, it cannot be hidden.
as it's not really correct to say that a journal itself can be hidden - you may be able to hide its contents, but you can't hide the actual existence of a journal.
And also add a line after the "other user pictures" paragraph that explains that all of your userpics are visible to the world at http://www.livejournal.com/allpics.bml?user=exampleusername, like:
Please note that anyone can see all of your user picture icons by navigating to http://www.livejournal.com/allpics.bml?user=exampleusername, where exampleusername can be replaced by any valid LiveJournal username.