I'd like to make things clear first.

If I understand correctly, the 88 ETH in question was already sitting at your metamask wallet when the unathorized transaction happened, no? If so, it'd be difficult to say bitcasino had hand on this when the ETHs were exposed to your system as well.

I understand that the hacking incident were on the peculiar side of things but it's not enough proof to say bitcasino was responsible for it. We can't also say you and bitcasino were the only ones aware of the transactions since we're talking about a public blockchain which many people are monitoring. I reckon more victims would've came along if bitcasino is truly responsible.