Hmmm. I'm guessing that yoke-shaped part in the middle slides left and right with differential flex...if that pin is removed. Otherwise with the pin in place the whole system is locked in place and the torsion bars are anchored as per normal for road use. Very interesting. I would love to try it.

[Edit] Duh, the first pic shows the pin out and the yoke part off center...can't quite make out how the torsion bar mounts swivel to accommodate this movement, but they obviously are doing it.