That is really sad to hear about your friends wife C-Bag. Even worse is hearing that a ROPS was fitted and she was thrown out, that means she wasn't wearing a safety belt. We now have training courses for farm workers because of the number of rural accidents. On the tractor safety course they teach to always wear your safety belt and if you roll cross your arms, curl and sit tight.
It may not be an automatic reflex in a rollover but with a bit of practice it can become automatic. A bit like riding a 'bike, you know you are going to drop it one day so playing a scenario in the mind ups the chances of survival.