[patio11]

Submit documentation of your conversation with him, including e.g. screencaps of the appropriate emails where he demonstrates that he, in fact, used the product successfully after delivery. Then wait. You may win and you may lose.

If Paypal finds you in the wrong and this is a $1k+ issue for you, time to speak to a lawyer. You presumably delivered this to an actual person at a real address in the United States, right? If FedEx can find him once to a deliver a miner it can find him a second time to deliver a nastygram and a third time to deliver an ITS (intent to sue) letter.

By the way: "is interested in Bitcoins" is a red flag for fraudulent customers. For a reason. You may wish to take this into account in your future business endeavors as on factor in your risk management.