I believe that it will not be a big problem if the participant receives a withdrawal to his wallet not after 1 minute, but after five. And if need to involve several additional people to make a manual withdrawal, then it will still cost much cheaper than searching for the stolen $4 million.
Well, if participants doesn't withdraw their money then that cold be more good for Meta run in long term but as we know they're allowing participants to withdraw the money and that means the $4M doesn't impacted their bankroll that much. However, we all know that $4M isn't a small amount for a new casino but since Metawin has been there for sometime and I believe they won't get impacted by that hack to high extent.