My cynical guess is that he doesn’t have the private key, but wants to use legal methods (court cases, registering copyrights for documents, etc) as a means of establishing himself as Satoshi.
Once established he’ll launch a court case requiring a hard fork of the blockchain to “recover” Satoshi’s coins, because they are after all his, and profit ... assuming he doesn’t crack the truecrypt password first.
Except he probably won't be able to create a hard fork; if my understanding of crypto / bitcoin is correct, he needs a majority of miners to go with it, and given that the Bitcoin is international that's going to be very difficult.
You don't need a majority of miners to create a hard fork, you just need any amount. What you need a majority for is to get the chain to adopt your version of history without hard-forking.
Once established he’ll launch a court case requiring a hard fork of the blockchain to “recover” Satoshi’s coins, because they are after all his, and profit ... assuming he doesn’t crack the truecrypt password first.