Your brother should review the T&C's of the ticket. Maybe they allow applying the value to a new ticket, in which he could then repurchase -- and possibly get more than 50% of the value. If this is the case, he could apply for a US visa, or if there are direct flights -- take one of those (if there are, I am surprised the airline did not put him on a NS flight).

I have also seen T&C's make reference to refunds in the case of improper visa's / denial of travel due to same. Maybe these rules will bear in his favor (or favour ).