[ubermeister]

The definitions say

HURDLE: When a TRACKBALL CROSSES a FINISH LINE while passing above the OVERPASS and then contacts either the floor or another ROBOT before re-contacting the originating robot.

HURDLING: The act of completing a HURDLE. To be considered in the process of HURDLING,
the ROBOT must:
• be in its own HOME STRETCH, and
• be in POSSESSION of a TRACKBALL, and
• be moving toward the OVERPASS and/or elevating the TRACKBALL so that the top of the TRACKBALL is higher than the LANE DIVIDER.

This makes it sound like you only need to complete a HURDLE to score points, and that the HURDLING definition only applies to the referrees making calls about IMPEDING:

Note that a ROBOT is not IMPEDING traffic if:
the ROBOT is in the process of HURDLING (except as noted in Rule <G43>).

So, yes, throwing it over is a legal and scoring move, but if you stop to do so, it is considered IMPEDING.

EDIT: Wait, never mind- I am confused too now, since I missed the line "The act of completing a HURDLE."