Ugly Sticks have a 20% horizontal tail area. Just excess rudder won't cause nose down unless there is a loss in horizontal tail effectiveness. You lose porportionally more tail tail effectiveness due to loss of dynamic pressure recovery when the tail is as small as the airplane in question. If it is just drag from rudder deflection slowing the airplane down both wing and tail see the same reduction in dynamic pressure and similar lift losses which would lead to some nose down but not as much as when the horizontal tail is wiped out.