I don't think it's a cop-out because the original post's question revolves why might we perceive these scenarios differently. I perceive them differently because one seems inherently or intuitively less reliable, even if the scenario asks us to believe otherwise. So the answer is to do with perception.

Given your scenario with attendant assumptions (I know Jared's heavy enough, I know the sharks will be released and kill the people in the tank --why not just shoot him, dad?--, I don't have any emotional favoritism between the people, I wouldn't face legal consequences, etc.), THEN I can say that I would sacrifice Jared. My answers for the two scenarios in the original post would also match.

I just thought that the question of why the scenarios appear different was more interesting.