Another bigger question to the ops is, why didn't he contact the casino when he received such unusual bonus from them, and from his explanation he receive such bonus twice and have managed to withdraw 50k-80k that is huge profits enough for the ops, and if he wanted to get any clear understanding on the terms and conditions on the bonuses if there be any then he should have first of all reached out to the support team of the casino to get the template for the terms and conditions of the bonuse before he started gambling with it.
So its still a win-win for the ops and I suggest he move on, but anyway, he already stated that the thread was meant to just warn others, who may receive such an offer from the casino.
Maybe it's not that they downloaded his betting history from Stake, like OP thinks, but he received the bonus by mistake and gambled with it, without reporting it as a bug. Rollbit saw their mistake and saw player as untrustworthy. Instead of making things clear to the player they banned him. It's strange behavior, I agree, but I don't get how a casino would know how much a player has wagered on another sites and give that player freebies just for being a high roller somewhere else.