Legally there can be no way because the clearly mentioned about the time limit to withdraw all users funds, and even if you want to take this to legally you need to spend huge so make sure you have huge amount to take this case.
Its impossible to retrieve or getting those coins back stucked into that account and probably all of those coins that had been locked down had already been used by the owner itself.
They do gave out timeframe on pulling out your funds at least into their platform and since he missed it then he do really had some mistake too.
When it comes to legal actions or whatsoever then its somehow pointless unless if we do talk tons of btc or alt value on here.