I did know about that and my understanding is that flight protocol called for Schirra to activate the seats on Gemini 6 but instinct told him not to.

I have always admired Schirra and Stafford. All suited up and strapped in ready to go, and then get cancelled moments before launch because the agena had blown up. Then to be ready again to go a few weeks later to hook up with 7, only to have this happen. And yet come back two days later and try for a third time, finally successfully.

I heard in a documentary a NASA engineer talking about the Gemini ejection system being 75% successful. Successful was defined as the Astronaut surviving the event alive.