In my humble opinion, there's a misunderstanding about the Gita. Gita is a part of the Mahabharata, and the Mahabharata story has made it very clear that Arjuna has only two options - either to fight or else to spend the rest of his life in exile in the forest. In particular, in the Mahabharata, Krishna has already provided Arjuna's adversaries the cosmic vision that he is going to provide Arjuna in the Gita - and that did not persuade them to make peace. The do-duty-without-fearing-the-consequences applies when there are no choices about the consequences. I believe Amartya Sen, you, etc., have made a mistake of considering the Gita out of context.