DPMA has nothing to do with FreePBX and is a Commercial Add on provided by Digium so we would never test for that. It would take Digium modifying their closed source DPMA stuff to understand extensions can be restricted on what parking lots a user can park at.
Its no different the the Call Recording button with DPMA does not honor any call recording permissions in FreePBX. Only Digium can do this since those features and apps on the phone are closed source.
Again the Dial Pattern is nothing we control and the first I have heard it will not restrict. Malcom also made it clear that it would not matter if it was DPMA or EPM configuring the phone that dial patterns behave the same