how much more is the refundable biz ticket than the refundable coach ticket? If it's $1k will you spend it?
Also, if there is something like violence in the country, chances are decent that delta would refund even a no refundable ticket.
Could you ask the client if you could buy a coach ticket and then You pay to upgrade yourself and if it happens to be cheaper you will pay them back the difference? Might work.
Of course if they are paying for you to have a refundable ticket you'd have to take the loss if you needed to cancel, not them.