After the self-destruct call was made, all the balance was transferred to the deployer of the contract. Why are withdraw requests still being processed?
After a contract call selfdestruct the code and storage associated with it is removed from the Ethereum's World State.
Transaction after that point will behave as if the address were an external owned account, ie transaction will be accepted, no processing will be done and the transaction status will be success.
Transactions will do nothing, but you still have to pay the transaction fee. You can even transfer ether, it will be locked forever or until someone finds one of the private keys associated with that address.