The best theory around that is, his investors.

* There's a mythical bitcoin fortune held by Satoshi.
* Mr. Wright had some investments and, at least in one, was using bitcoin as backing.
* Mr. Wright got goxed and lost a considerable part of his fortune there.
* His investors are pressing in, in sight of total loss.
* He got the magical aura of be holding 1 million+ of bitcoins, that he can't move right now for any reason.
* His investors rest a bit and ease the leash, giving him more time to breath.