At the top of each discussion thread there is a "Latest reply on <date> by <name>", followed by the RSS symbol.
But if the reply was by a not-logged-in user, the name field is missing, making it look like the reply is by RSS.
In other places, such as "in response to <name>" at the top of each reply, the <name> does work
properly for not-logged-in users.
Because of the way the Jive CMS handles guest accounts this behaviour probably won't be changed, based upon past attempts at raising issues with the guest account with Jive.