I'm surprised they don't design the seats such that they pop out two bars under your armpit so that you transfer some of the forces into your shoulder and collar bone instead of just the spine.
Same way car seat belts horribly injure people if they let it rest on their stomachs instead of on their hips.
The forces involved would only pop your shoulders and not provide any support for your back via your underarm. And the speed the bars would need to come out at, might end up inside your chest cavity. The ejection seats are a last ditch save from certain death. I’d take the loss of an inch or two to my height than the alternative.
Not a bad idea at face value but as opposed to seatbelts it introduces additional complexity that has to handle every eventuality including G forces from any direction, and still function perfectly. Probably has failure modes that increase injury risk. But this isn't a bad line of thought to go down, ultimately.
2) Think your shoulders could take it?? It's IIRC ~15g.
I do think they probably could make a gentler ejection mode as the seats are built for the worst case. The lower your airspeed the longer you have to get high enough to clear the tail and thus less acceleration is needed.
Same way car seat belts horribly injure people if they let it rest on their stomachs instead of on their hips.