True, these three movements have caused injury to some BB'ers and lifters in general. But than again, so have benching (incline/flat/decline). Squats, DL', lateral raises and even simple curling..
With regards to the PBN & Up-right rows, one of the many causes is poor hand spacing/grip position, rushing the weight (using too heavy a weight before really ready for it), no warm-up/stretch before lifting & ROM. Last. but not least, God awful exercise styles. If feeling uncomfortable, or even a hard strain, doing these exercises...than may want to check the exercise style and form. No matter how much any "expert" may rave about the benefits of any movements, if not for you..than it's not for your body makeup..
The Press Behind The Neck (or Behind the Neck Press...whichever) and Up-right rows have been favorites of mine for years. Even SS'ing them in the same workout, which I have mentioned many times in the past.. Have also used chins behind the neck, on occasion. without any problems. SS'ing those also with regular front chins. Never having suffered any form of injury. But that is my individual experience, more than likely that may not be yours. No one responds in any exercise in the exact same way.
Just some general observations, take them for what they may be worth, or not be worth. Not being critical of Arnold, he be the man. Though I prefer Sergio as the top 1# BB'er..just my view.
If that extra wide hand spacing of Arnold's worked for him (and it most certainly did) than good. But for most guy's his wider grip places too much stress on the shoulder joints themselves. A closer grip, nearer the shoulders, sets the leverage more on to the actually delts and triceps (the pressing force) and avoiding joint stress. Also not much of a need to press the bar much higher than the top of the head, if building delts is the prime goal.
With Arnold's Up-right's (which seems more posed than taken during his actually workout) , the better advantage would be to have the hands placed closer, for most guys. Raising that bar to than height, with that middle grip, can give undo tension on the shoulder joints. Also the extended stress on the wrist and forearms. Keeping the bar close to the body (almost touching) can also reduce joint stress. If the bar travels out and away from the body. than more leverage and stress are placed on the shoulder joints.
Good Luck.
The last few years I have been using a Ez bar for Up-right, and find even less stress ont he wrist.