This shaft is a part of the drive for the elevon yaw compensation*. It is positioned at an angle in the rear fuselage section in close neighborhood to the vertical shaft of the rudder controls. The top of the shaft carries a wire pulley, the bottom one has a swan-necked lever bolted on.
The flanges were welded to the tube first. Only then the bearing shafts were turned to size on the lathe so they come out parallel.

*Yaw compensation
Flying wings have a pronounced tendency for yaw generated by elevon deflection. This effect is automaticly compensated by a rudder tab on the N-20.2 .