If quantum threats become a reality, simply distributing Bitcoin will not be enough. Hard fork will become a necessity!
No, that is wrong. Don't listen to social media experts. Everyone is an expert on everything online, but in reality almost nobody is an expert on anything.
It wouldn't be enough in a general sense of things, but if they never spend from the wallets they have moved their coins to, then quantum computer would be unable to derive the private key from the public key. Take note that once BTC tx's are made, the public key is exposed and is public, and that is where the threat of quantum computer lies, in breaking ECDSA and generate private keys from public keys, something classical or conventional computers cannot do.
When you deliver the message like this you are ignoring most of the important information
relating to assumptions and nuances. It is assumed that the derivation will be possible, and that ECDSA will be broken. Nobody at this point in time knows exactly how much energy one derivation will require, nor how much time it will take such a machine to derive it. The devil is in the details, most of it is unknown and the rest is theoretical.
Only once it becomes feasible to do this at all will we know more about it.