Similar thing happened at Akrotiri in the mid 60’s. A Javelin suffered a shattered canopy whilst in the circuit. The pilot, over the noise of the slipstream shouted to the Nav, “if we have to, will you be able to eject?” The Nav heard the key word ‘eject’ and did so. The pilot managed to land safely, the Nav was picked up in Episkopi Bay!
With regard to non-aircrew backseaters, I can’t help feeling that, in spite of all the safety briefings, ( of which I’ve experienced) the split second reactions required in an emergency, are possibly not as sharply honed as experienced Aircrew.