well he is technically correct in that yes a displacement map (one that is made by sculpting a higher res version of the figure and generating the map) is a dervitive work and therefore 'could' be disallowed by the holder of the IP rights...

.. but to suggest that they wouldn't allow that is a bit of a stretch..  The key principle that anyone in the poser content business ought to follow is that as long as you arent circumventing people needing to own the product or using one figure to enhance a competing figure its likely going to be OK.  Of course that is entirely up to HW3D.