G-Code supports three movements:
Straight lines
Clockwise arcs
Anti-clockwise arcs
Any wiggly NURBS curve in Rhino that isn’t a line, a circle, or an arc needs to converted to arcs before being used for CAM.
Use the Convert command with the angle tolerance set to zero to disable it.
Use the command option tolerance to set how far you’ll allow the replacement arcs to pull away from your NURBS curves.
The dots in the preview will give you an idea of the number of arcs you’be be replacing your NURBS curves with.
Give that a go.