If Satoshi's Bitcoin wallet moves then he is still alive, at the time if anyone comes out to say he is the real Satoshi just base on words nobody will believe, even if he is the real person until....

1. His Bitcointalk account become active again.
2. Small BTC is been moved from his wallet.
3. Do some verification or sign through transaction.

But a question remains, why would he want to do this? It is part of his protocols to remain anonymous, because this works better with Bitcoin as it's a decentralised digital currency.