This is how it was designed to work. Considering how the rest of the module works I don't have any plans to change how this works in the future. Private Forums are not exposed to site search, RSS or Aggregated Forum view.

It's never anyone's goal to take the easy way out. Please think before you speak from now on and understand the possible security issues if the wrong threads are shown here as well as understand how the module uses cache to increase performance then comeback here and post something informative.