Actually what they are saying is that above a certain speed (around 230 kts) that the force required to get the rudder moving is virtually identical to the force required to get it to the full stop.
So once you clean the aircraft up the rudders aren't controlled in the conventional sense. You should consider the rudder pedals full left and right toggle switches. Something that would guarantee an overcontrol should you suddenly need them in the heat of battle (which is something you might go your entire career without needing, like an engine failure, but that one time you need it, it will let you down)
Cheers
Wino