JP:
Some folk will try anything to avoid the facts that without any doubt whatever (as we say) the crew should have turned away from that cloud-covered hill; and without any doubt whatever, they failed to do so.
Well no quibble from this folk, JP, for I fully endorse your quote! Catch him someone, I think he's fainted! As to your list of "off beat theories:
1,3 and 6 all stem from variations of Walter's scenario and, before he has a go at me, probably misrepresent it to boot.
2 and 5 I suspect were offered as examples of how an aircraft under control could finish up in a CFIT.
Which leaves 4. Again over egged as no-one to my knowledge has said that all the controls jammed (though it was a feature of the control pallet that they could have done). It is also in poor taste to say that if that were true that the pilots would merely have sat there helplessly. I suggest that they would have fought with the condition to the very end, whether the jam was in 1,2 or 3 axis.