If its showing as completed in YOUR Paypal account then you have paid, the fact its pending on the SELLERS end is between him and paypal as he is a new seller. He is supposed to send your item promptly (trackable to prove delivery) and then his funds are released when tracking shows the item as DELIVERED + 3 days.
He is at no more risk now than if he had the funds in his bank account, the hold is to protect PAYPAL from new sellers that don't refund buyers in the event of a dispute (then paypal have to refund under buyer protection).
Tell him if he refuses to send then you would have to file a dispute for non receipt of item and that would impact on his paypal account as such an early seller and the time the 'new seller hold' lasts would be extended OR he may not be allowed to sell.
