Why is leading edge damage likely if there is no visible moisture? I'm keeping an open mind to the possibility that you are correct but I can't see how the visible moisture prevents leading edge damage.
Scenario 1: Minus twenty degrees TAT and no visible moisture.......QRH instructs you to turn the bleed off.
Scenario 2: Minus twenty degrees TAT in stratus and the bleed stays on. How does the stratus prevent leading edge damage?
Thanks again for your thoughts.