yeah, but posts braking can also turn the barrier into a spring, pushing the car back into the track and launching it in the air.
In this case, it didn't launch, but if you look
here, you'll see the SEAT Leon was launched, back, into the ground and then into the air. Apparently the posts are/were rotten and broke. Not the first time this has happened at that (brands hatch) circuit IIRC
Hines' accident could have been so much worse if that had happened, or if another car had clipped it. He's a very lucky boy