The point is, mixed with the knowledge that controllers consider "clear of the runway" as everything to the right of the outside WHITE runway stripe in that photo...
It's easy to get an aircraft off of 17L/35R at KAPA without reversing course at all.
As long as your not in a G-V or a big Challenger or one of Key Lime's Metroliners, that is.
I bet Teller could even squeak a Piaggio off without more than 90 degrees.
Other airports, YMMV.
We're all thinking the same thing I think here.
a) Your FO friend's Captain had his head up and locked.
b) He picked the wrong person to mess with that day.
c) Nobody can find that there is any "pattern" of this rule being used regularly for enforcement.
The "warning" seems a bit over the top in light of all of the above. Most controllers and pilots simply don't care as long as the "expeditious" flow of traffic is maintained.
The warning realky should read: "Screw up the landing sequencing when a better option is available by going the wrong way into a high-speed, and then argue with the tower on the phone about it... someone's probably going to make your life miserable. You're also going to screw over your crew (FO) who's going to make sure everyone (s)he knows, is forewarned that you're a nimrod."
That pretty well cover it?