I don't think moving old coins could very well be hidden. But, I believe the reason people say that old coins are more likely targets is because a person with a quantum computer doesn't have to race to crack the key. If they target a transaction in mempools, they have to crack the key before the transaction gets mined.
I don't think moving old coins could very well be hidden. But, I believe the reason people say that old coins are more likely targets is because a person with a quantum computer doesn't have to race to crack the key. If they target a transaction in mempools, they have to crack the key before the transaction gets mined.