Thank you as always for your thorough replies. I’ll split them up next time. I took notes while watching, then compiled my questions not answered by the end.
(Greenspun only had 1 “rule”, about complex programs containing an ad-hoc subportion of Common Lisp (later amended to point this finger at Common Lisp itself 😉 ), called it his “tenth rule”, but had no other rules. Which one were you referring to with the seventh?)