That photo is the result of the simulated machining, right?
There is a setting in RhinoCAM that lets you change the rendering options for the simulation. Unfortunately I don't have RhinoCAM (or Rhino for that matter) installed at the moment so I can't find where the option is for you.
Look around in RhinoCAM for "Simulation Settings" or something like that. The simulation geometry settings should be in there somewhere. If I remember right the "inferior" option is called "voxel" and the better option is called "polygonal".
... Attached is a screenshot of the setting I'm talking about from the RhinoCAM 1.0 manual (sorry, I'm too lazy to find the 2.0 manual, but I bet the windows look similar).
Location of 1.0 manual: http://www.rhinocam.com/Downloads/RhinoCAMTutorial.pdf
I hope this setting will fix the look of the model, but I'm not sure it will. I hope I haven't wasted your time.