Well, Peter, I'm talking way back in my own history, too: I started in professional photography back in 1960, which is probably further back in personal
and relative times than did Alain.
Please don't tell me about darkroom procedure; I earned my crust in those places for, literally, decades and then managed to escape the dark art for the brighter one of Kodachrome.
Line film: for making high contrast negatives of print (in the sense of writing or line drawing) and similar original metarials. It came in sheets which you handled and developed under a red safelight. It could be used for anything, experimentally, where you wanted to lose mid-tones and have just black/white.
https://en.wikipedia.org/wiki/Purkinje_effectThe above - from Wiki, so yes, Dr Google is your friend if you speak to him nicely - will give you an idea of why Kodak and Ilford recommended the colour of darkroom safelight that they did. Darkrook vision and, consequently, filter recommendation is not governed solely by paper safety: it is also governed by how the human eye adapts to the different forms of illumination within the paper's safety margins.
As to your question of how one handles paper under anything but a red safelight: in exactly the same manner, except that using the paper manufacturers' recommended yelllow/green/amber variations allow your eyes and brain to see the developing print more closely to the manner that those same human tools will perceive it in daylight.
I never did state you
could not use a red safelinght. I indicated that nobody in his right mind does that, ignoring the paper makers' advice, and making life difficult where it need not be.
As for trying to stand on Mt O - disabuse yourself: I did that back in '60 when I got into this business (and remained in it the rest of my career) and within days learned that I knew nothing, relatively speaking. Do you own a mirror, by the way? ;-)
I am not dismissive of Alain and neither am I in awe. As artist he has his style and, if it sells, good for him. That's the name of the game.
Rob