Several possible explanations:
1) Perhaps he's decided to quit the site, and feels that timing out would be rude.
2) Perhaps he feels that he has far too many games going, and only wishes to continue the ones that he finds interesting.
3) Perhaps he is just trying to practice openings, and playing out the rest of the game takes too much time.
4) Perhaps his cat has gotten access to his account.
5) Perhaps he's sand-bagging... intentionally dropping his rating so that he can squeeze into a lower bracket in an upcoming tournament.
Was in the middle of a 3 day game vs some player....21 moves in and I log in yesterday and he's resigned the game in what I thought was a good positiong for him. That's weird I think...maybe he hit the wrong button. I check his game history and see that his last 40 or more (I stopped checking) games have been lost...all resigned. The player's dropped hundreds of points in the space of a few hours.
Why would he have resigned all those games? Is it a glitch in the site? What's the deal there?