I'm not near mine right now but remember having the cushion out and sitting in the seat. I remember it being hard as a rock. I'll take a closer look at it this afternoon and see exactly why they would call it a suspension seat. I will test it to see where the platform might be open in the middle to allow and suspension movement.
I included a picture of the gen 1 seat bottom side that someone had posted before. You can see that it is truly a suspension seat as it is completely open on the bottom side and only supported by the suspension strings.
Stephen.