Not to mention that in his feedback, he has sold nothing but comic book related items with a top sell price of $325.00. Now he suddenly has a $14,000.00 - $15,000.00 gold coin for sale? I'd say his account has absolutely been hijacked.
Images appearing to be from different sources could be legitimate but qestionable, the database failure could be legitimate bu, a refusal to use Paypal could be legitimate, put all three together and it seems VERY questionable. I would suspect the key it the paypal refusal. He hopes to get your money, you don't get the coin and ebay/paypal wouldn't be able to recover the funds from him.
Call PCGS customer service and ask them. Occasionally, a typo will be made in the database and a legitimate coin and cert. number won't show. On another note, not accepting PayPal is a huge red flag in my opinion, so be careful.
Now seeing the images from the auction, why is it that there are two different images using two different photography techniques on two different backgrounds? Run! Also, can you refuse to accept PayPal on eBay? I don't think you can.
The OP (or anyone) isn't likely to just walk into a shop, legit or otherwise, and find one of these in unc, or even what passes for unc these days. This, if genuine, is the type of coin that can take a little patience, even if one is willing to settle.