A sale is a sale.
Ship.
The 'no international selling' policy is probably a Buyer/Seller protection set up so that naive buyers don't get taken by unscrupulous sellers ( Don't worry! It takes longer to get there from Tanzania! I will send a replacement but just wait another six months!) or buyers (The package didn't arrive! I want a full refund and $10 for my heartache! BTW the stamps on the package were very pretty.)
You may not be able to print out a shipping label through Paypal.
Do not ship until PP tells you the money has been received. Keep in mind that they will Hold it for 21 days. Another Buyer Protection.
Don't be surprised if your Dutch customer has an American address. Trans-shipment is a big business. As long as you can show the coin arrived at the trans-shipper you are fine.
Only ship to an address supplied by Paypal.