I never heard of BC.game deactivating accounts for inactivity.
So far, there have been no issues with accounts being deactivated due to inactivity.
As far as I know, BC.game does not enforce this rule.
I did not know other centralized exchanges or online gambling sites have that similar term like Poloniex and like you, I glad to follow it up from this discussion with more details on this term at BC.Game. If the term is truly applicable by BC.Game, their users must be careful and if they plan to be inactive for a long time, they need to withdraw their money from accounts, just in case.
here may be differences between casinos and exchanges in this regard.
However, BC.game does not mention this issue in its terms and conditions. If you are concerned about your account being inactive, it is best not to keep any balance in your casino account.