I think this misses a couple of key points. The only reason his car tore in half and caught fire was because the barrier failed spectacularly. It’s absolutely not supposed to do that. LeClerc had a bigger crash in Monza this year, and it wasn’t nearly as dramatic. So this incident was caused by a piece of safety technology failing catastrophically, with a whole bunch of other safety tech working as intended to save his life.
Also it’s good the marshals and medical crew were there so quickly (as the medical car follows the pack on the first lap). But they basically contributed nothing to Grosjean’s survival. He was completely engulfed in flames for 18 seconds. He survived because his flame protection worked (he got his burns from using his hands to climb over the hot barrier, not from exposure to flames), and because he wasn’t incapacitated by the crash. If he had been knocked unconscious or injured too badly to move, he would have burnt to death in there. The couple of fire extinguishers they had on the car weren’t doing anything to a fire of that size.