Am I making any sense??
Well, to me, sort of. A very fine line you have drawn with
Because nebulous statements like "the Captain must have ultimate responsibility for the safety of the flight" implying therefore, that this was pilot error, are facile in the extreme
Followed by
Now, the Erebus crash *was* due to pilot error, but for very specific reasons - not because the Captain failed in some ill-defined ultimate responsibility.
Your second paragraph I would agree with until
"the Captain has sole responsibility once the wheels have left the ground" as if they mean anything (which really, they don't) serve only to entrench the belief of the Mahon camp that those who would ascribe this to pilot error are nothing but a bunch of conservative reactionaries who don't understand modern aviation or teamwork.
I really cannot see any reason why this should be so, perhaps you could explain why you think it would be so.