Presumably only someone born in 1971 (Ben Zimmer) can consider 1975 to be ancient history?
 It seems everyone has lost interest here but I made an effort to make some sense of this. 
 The article was confusing 3 entirely separate uses of the term, a red line (a line in the sand), a Thin Red Line (a brave and defiant stand against great odds) and to redline (meaning to go beyond an engine's maximum safe performance level). I am sorry to say it, but for someone who claims to be a"lexicographer" and language editor, Mr Zimmer ought to be ashamed.