More seriously tho....

If you suspect that a buyer is playing games in order to get a refund, and you are very certain you will lose the INAD case anyway, I would always advocate making them jump thru the formal ebay hoops to get their refund. ie raise a formal INAD case. Open cases do not get you a defect any more (as they used to) so its quite safe to go this way and refund them immediately via the case. You only get a defect if you fail to resolve the case and ebay step in to do it.

Doing it this way it forces them to record this kind of activity on their buying account. If they are frequent offenders they may not be too willing to go this way. Of course they could give you a big RED dot instead but you may have a chance of getting it removed going on the prior communication between you and the buyer.