I posted this detailed analysis describing a likely motivation for Craig needing to "prove" he is Satoshi.
https://www.reddit.com/r/Bitcoin/comments/3w9xec/just_think_we_deserve_an_explanation_of_how_craig/cxuo6acThe short version is that he made fictional investments in a company by claiming to have transferred his personal "interest" in $29m of bitcoin to the target company. (I.e. no blockchain transfer, just a legal document claiming to transfer that amount of bitcoin.)
He then claimed substantial
cash R&D credits from those transactions.
Australian taxation office (ATO) began investigating. He has paperwork showing the transactions, but knows that ATO might dig around and want to see verification that he truly owned $32m of bitcoin. To cover that, he claims he put all his bitcoin in a trust, where the trustee was another early bitcoiner. Unfortunately, that friend has now passed away, and the private keys are lost.
In order for the BS to be even vaguely plausible, he needs to show that he originally had access to $32m of bitcoin. This is why he pretends to be Satoshi.
