my only guess at what they would say is that neutral is more natural and all their training has to do with mimicking movement in real life. sort of like why would you ever do the pistol squat in real life – the shoulder width squat is more natural to how you would normally move – so while you may go for pistol squat, it is great to get there but it has less resemblance to actual movement.  so even though the ultimate goal is to hang with palms facing you and touching thumbs, you’d rarely find application of that in real life.  it’s just their philosophy on training.

now having said that, perhaps one would argue that you may encounter the palms facing away situation more often in real life movement, so that is the position you should practice the most.  OTOH, it has the least external rotation at the shoulder, so neutral has more and is more stable, and turning the palms towards you as even more external rotation still.  would that affect shoulder problems or not?

in other text, they talk about not using straps but only your grip to hold on. if you do, you reduce the possibility of injury because gripping irradiates activation of the entire arm and shoulder stabilizers to support properly. the moment your grip goes, its your body telling you your stabilizers are fatiguing and to save yourself. however if you strap in, you risk shoulder damage because you’re still hanging there without the proper muscle activation to stabilize and support. so if you go with this info, you might say that palms facing away is fine as long as you are gripping and activating the proper muscles to stabilize….

food for thought…!