The halo saved his life, for sure, but he also had a lot of luck on his side as well.
If the car had got wedged just a little further back in the armco, so if it had rebounded back a little after the roll bar hit the armco and stopped him, the armco across the top of the halo would have made escape impossible. That's not a negative on the halo, just an observation on the circumstance.
Lucky he didn't get knocked unconscious too, as already noted.
The gap between the rows of armco should be removed, by designing them to interlock, unless they become a one piece section. The gaps, or even a missing bottom row of armco that you see on many roads and motorways are a massive danger, especially to a sliding biker too.
The armco was mostly going in the right direction Tony, it was a blunt hit purely because he was veering across the circuit at that point, if he had just run wide earlier, and was still going in the right direction, there would have been a much simpler deflection.
On a lighter note, it was strange to see him escape and jump from behind the barrier over to track side of the barrier to get to safety, when he was already on the safer side. I am sure that was instinct kicking in, when stood up in the cockpit and feeling the armco to hand, jump over it away from the fire, as well as seeing someone trying to pull him clear.
Did you see that his visor appeared to have melted a little too, although i am unsure if that would just be the tear off strips that melted, making it look like the visor had too, as i would expect the visor to be a bit more resilient than that?