Rad girl.rather than explain your logic you've simply repeated yourself. In considering risk, we measure by present day comparitors not against some arbitrary point as you've done, in the 1970's. A 777 with one engine out is probably safer than a Vickers Vimy with two. By your bonkers logic it would be ok to dispatch single engine.
The fundamental point that you're point-blank refusing to address is that medical risk factors get much higher with age, especially above age 65; it's not an arbitrary point. If you lake the trouble to look at the report posted above by swh it explains this graphically.