Although I do not profess to know the exact nature of the non 4WS rear suspension set up (as compared to say Eddy or Ardub), it would seem that it is indeed passive rear steering from the description - same as on certain Peugots and also even the 8 series BMW coupe.
Without getting into a definition debate, it is my understanding that if there is a deliberate design of the rear suspension/rims etc etc so as to induce a simultaneous change of the rear wheels in aspect and direction of travel when the vehicle is turning X degrees, and such change of aspect differs from that which occurs when the vehicle is travelling in a straight line ('normal') , and such aspect change will revert to 'normal' upon completion of the turn, then to me that is a 'steering' effect . Passive - no steering rack, active - steering rack.
My fuel for the fire!!!
Jamsvx
PS: thanks for the kind comments on my web page - I will eventually clear up that horrible intro page!