Everyone in the gridseed groupbuy received their miners or a refund except your brother,
I don't think that really works as a defence, you're admitting a debt but saying its his [his brother's] fault you owe him money. It doesn't stop you owing him the money.
I owe him his miners but am unable to fulfil it because he is withholding his shipping address. Thus I can not provide his miners and for that reason I am auctioning them off and will send the proceeds made from the auction to him as that is the only way I see that will work in this situation.