I think he was trying to say that most rear cages are used as a safe place to mount to harnesses at the correct degree eg less than 10 degress not 45 directly to the floor, if you roll the car you'll more than likely compress your spine, not to mention you can generate up to 10 G's in the event of accident. I don't know what you guys use to fix the rear harnesses to the floor but it needs to be something very secure!
I'm not sure about the clio but I'm guessing looking at that cage it doesn't attach near the rear strut pick up points so does little to improve handling.
It's only function would be in a roll.