If I'm understanding you correctly, you wish to use a poser model as a "model" for a contest image? The intent of the Poser software in the beginning was as an aid for artists who wished to work from models to create figurative work. Essentially a life drawing class in your computer with virtual models that the artist can light and pose for reference.

"is a 2d artwork created by inspired 3d art created by the 2d artist less original than a person who copies a photograph?"

nope.

Poser is an artist's tool first and foremost,  whether it be used as a reference or as a canvas in itself.  Realism, still-life, comics, pin up, whatever.  Beyond this it's difficult to speculate how others might perceive your use of the software.