Did you ever consider the fact Satoshi doesnt want to pay his billion dollar tax bill and thats why he shows proof only to those who matter and not the retarded general public who cant understand what is best for Satoshi s personal and financial interests?
Though Satoshi's country of origin is still unknown, it's likely only a taxable event if he sells them.
Regardless, it would only prove that he owns however many coins are at the address he is signing the message from.
Wright isn't signing a message from one of Satoshi's addresses because he can't.
Australia, and I dont think Craig has returned since. Pretty relevant.