If you research what Oregon Aero has said for many years regarding the safety of their seat design, you will find that they said the seat structure itself was designed to have near zero vertical energy absorption. The reason being that it is impossible to prevent the rebound of that energy back into the spine of the occupant, with this type of seat. The dissipation of the energy is done with proper design of the foam cushion system, using foam that can take an instantaneous compression under load, and then be highly resistant to rebounding that energy.
So with a proper cushion design, a very stiff seat bottom is actually desirable, to assure no deflection (absorption of energy) that will then be released in the opposite direction.
Oregon Aeros claim was that their fabric seat bottom was specifically engineered to have very low deflection under crash load.
BTW, my understanding of why an in house seat solution was designed is that it had been a struggle for many years to get Oregon Aero to deliver seats, and when they did the cost was constantly going up.
