I never hear rules like that. That is seem crazy.
But we know gambling company get money from your gambling not for saving your money.
So... that is fair.. if they giving us atleast information about it when our account going dormant account.
Email the customer is enough. Let them withdraw remaining money..
If they taking action by itself, that is not different like ponzi scheme and that is hurt for the customer itself.
Gambling making a consistent bet in gambling is what gives gambling website more money and it's obvious, but having a dormant account in gambling is something that is different from my perspective,
As I may seeing dormant account in any gambling platforms, it doesn't grant any thing or bring anything at home, that is why i strongly believe that gambling get more money once people play more bet in it.