Heck if you do have proof that he added the paypal fees on top of her purchase price, bring that up too. It at least will be a ding on his paypal record.
Also....as a side note, be wary of anyone requesting that you pay as Friends and Family because they are trying to avoid the business fess and that can be a ding on you as well. And you don't get buyer protections.
I hope they do decide in your favor on that especially if he said he would refund in private message/email. Paypal can be very frustrating to deal with in matters like this. If you have proof that this is the same email on his paypal account saying he'll refund you, that should help it go smoother.