OP said

"I am trying to make a universal script to "clear out all the unwanted items", ahead of the user making a Preview render in Poser 11. One of the many such unwanted item is the DisplayOrigin points (aka the 'green rods'), which you can see here."

OP is trying to clear out unwanted items, in this instance origin displays in preview render. Origin displays do not appear in preview render unless you methodically turn them on in every actor. OP says these are appearing by default in his scene, which indicates his installation of Poser 11 has some bug. It's not typical Poser behavior. In his above illustration, for example, I'm seeing primitive ball, Andy's wrist, and Andy's neck showing origin indicators. Which normally would only show if you were to activate that feature in each actor's parameters. The feature is off by default in all instances. OP indicates that it on by default in his Poser scene's previews...