This is just cr*p. Just because some rich kid/doctor/banker can afford to buy a Cessna but not be bothered to read all the warnings about worn seat rails over the years , why should Mr Cessna's excellent company ( and I've no axe to grind- I fly a Piper) have to bail then out. Of course the real story is with the lawyers in the USA who operate the monstrous no-win no fee scheme (its here too folks - viz Claims Direct).
Its like a motorist trying to sue a tyre manufacturer when a worn tyre bursts with the inevitable consequences. Are worn tyres design defects?
Read the AIDs and fly happy