Welcome DC8rider. I'd completely forgotten about this thread!
I'm not necessarily agreeing with this, just passing on what I was told. Everything you wrote is of course 100% correct.
At the end of the day, I have to say I'm not quite sure anymore who ultimately "carries the can".
My thinking is along the lines of the TechLog; once the commander has accepted the aircraft (ie maintenance release), is he/she then ultimately responsible based on that signature?