New 9.0 Adjustment Entry functionality - allows orders to be entered?

 We moved to 9.0 about 9 months ago, and were very excited about the new Adjustment Entry functionality on the P0006.  After setting several BUs to Adjustment Entry Only (and updated the adjustment doc types in UDC 09|AA), we discovered that this does not keep users from entering purchase orders against these BUs.  However, it DOES keep AP from vouchering the orders.  We are using encumbrances, so I would think that, when the order entry tries to update the PA ledger, it would trigger an error "Adjustment Entries Only".  But it does not.

This is really affecting our ability to use this functionality, as purchase orders and payroll are the items we want to keep from posting to certain BUs, while allowing accounting to make adjusting entries.  We have had to go back our old way of setting the BU as non-posting, then opening it up each time accounting wants to make a journal entry.  Therefore, the functionality we were so excited about has no value to us.