If there is a major problem onboard, then I don't think a suggestion that PIC has zero responsibility will fly.
I know what you mean, and in this case it is also a question of who created the major problem. What is unfortunate to this bar-room discussion is we may never know the outcome of any UAL internal enquiry. I'm sure we will discover the outcome of any claim by the pax. That will be very public. The night off the long knives will be very private, I'm sure; unless some one falls on their sword conspicuously.