Not enough information.
2 or 3 hours? How long actually?
showed signs? when, what?
subsequently passed away when?
what about medlink (you tell us, but you weren't there were you?)
Chances are, a highly professional combination of crew on board,
ground medical advice, quite possibly helped by medical professional(s)
who are so often available on board, and other factors (the late pax was from
ORD...etc) led to the decision to continue.
Quite probably a decision was properly made that the 300 pax to ORD
and the 300 pax back to ICN did not need to be disrupted by offloading
a deceased pax at an inappropriate (for her/him) location.
I'm familiar with this kind of event, and the dynamic completely changes
if the patient does unfortunately pass away. Difficult feelings for pax in
the immediate vicinity have to be balanced against the 600 others
involved. I have a strong feeling that 10 hrs trauma for an economy
section would not have been quite like you make it sound, especially
if compared to making an unnecessary divert to a place not beneficial
to the patient