Edit: This is important. If he was affected by Sandy, then it may be an issue with the carrier. One of my trades was "lost in the mail" for 3 weeks before finally arriving at a local post office.
He seems to have been online recently (actually today); however he has yet to view your messages. These can be checked by hovering your mouse over his icon next to his name and checking his profile -> trades -> whether there is a speech bubble next to trade.
In my experience, I have never had an issue with anyone on this site. I do often get people to send to me first; however, with 30 positive rep, I probably would've simul-send with this guy. Did you guys get him to send with D/C? For a trade that large, I probably would've expect to see a D/C number the moment he marked the trade sent.
Personally, I have had cards in PWE come in surprisingly long time periods (3 Weeks was the longest). I would try emailing both the deckbox support and him to see if maybe he's just having some problems. If not, then with so many people, you might want to try a mass mail fraud report to try get something going against him.