Presumption would be ultimately to live to wheel another day.
If it's a cage design issue that says 6 months healing your broken legs before you can wheel again, then maybe it met the function standard but not to the performance level that would be preferred.
But, I only know what you've said and you specifically mentioned no room for feet, no idea why there was no room. Was it the cage? Was it the seat location, harnesses not properly cinched down. I don't know what I don't know. Nor am I versed in the offroad racing world or anything with cages.
Broken legs despite the (presumably) proper and required restraints might fall into the caution of predicting the future to cover all combinations of all possibilities for how an event will play out.