The legal standard is usually where the party actually knew or where a reasonable person would have known that the access had been taken away.  Damages would be limited to the value of the bitcoin at that time. -- which is presumably not much or they wouldn't have ignored it.

Of course, an ambulance chaser lawyer could no doubt be found that would take basically any case with the hopes of scoring a settlement payout for themselves well beyond anything deserved just to get them to go away.

I feel bad for everyone who has ever run a bitcoin service, now exposed to a lifetime of claims for increasingly absurd amounts... often over imagined balances that never existed or were withdrawn and forgotten.  But even when they were real, over amounts that were inconsequential at the time.

I never did, but because I used to be listed on the website I still periodically get emails from people demanding and threatening me to give them access to wallets of bitcoin fortunes they claim they purchased in _2004_ or other impossible years.  I can't imagine what it's like for people that actually did hold coins for others at some point.  I also get insane messages because I was one of three potential signers on an escrow for a hack recovery bounty once, totally crazy.