Yes, we are in the phase of saying "the aeroscreen surely saved his life" several times a year. It's possible that something in the sport did happen that exactly coincided with the introduction of aeroscreen that made the sport 1000% more dangerous such that several drivers each year would die if not for the timely introduction of halo/aeroscreen. However, the more likely explanation is that the benefits of halo/aeroscreen are overstated. Something can both be beneficial and yet have its benefits overstated massively.
Bryan wasn't lucky in that accident. Unless his cockpit collapsed from the impact, there was no trajectory that Barron's car could take that would hit him in the head. Barron would have to be launched in the air and be coming down with just the right timing to clear the front roll bar but not clear Bryan's head.
Bizarre claim given the complete lack of protection ahead of Bryan’s head in those cars. Not sure where you’re getting this front roll bar from either. Single seaters from that era never had them. It was just the top of the monocoque. Just look at the thing.