So when the Captain is sitting alone at the big oak table with his little glass of water facing a multibillion dollar prosecution making their case to an administrative law judge who assumes guilt until proven innocent, will that be an adequate affirmative defense? Likely not.

If you want to make the case that both pilots should be responsibile then fine. So should the dispatcher. And MX. But no one is more legally responsibile than the Captain and that's never going to change. The mentality that its the other pilot's book so whatever it must be good simply cannot be codified into a company manual to that extent.