This section of the rules states that only the wheels of the scrambler can make contact with the floor. Does this mean that the falling mass can't make contact with the floor?

Only the wheels of the Scrambler and any parts of the Scrambler in contact with the floor at the ready to run configuration are allowed to contact the floor. If any piece falls off the Scrambler during the run, it is a construction violation. Therefore the falling mass cannot touch the ground at any time.