This is just inaccurate fud. We have no reason to believe that Satoshi is still active in the community its been years since he has been involved and Bitcoin has developed without him for a long time. Yes he is someone to be respected but for all we know Satoshi could well be dead or imprisoned. We will know when to make the changes that are needed for quantum computing by monitoring the development of quantum computers and not because someone decides to move their coins.
Given that Satoshi's coins are in Pay to public key outputs, the pubkeys are publicly available already. So if we assume Satoshi is dead or otherwise gone, his coins moving would actually be an indication that Quantum computers exist because the only way for them to move (assuming he is no longer around) is for someone to have been able to compute the private keys to those exposed public keys, presumably via quantum computer. In general, it would mean that the ECDLP is has been broken in some way (regardless of QCs) and should no longer be relied upon (i.e. we should move off of ECDSA and Schnorr).