The casinos themselves aren't necessarily currently against our policies. It's kind of a catch 22 though, wherein the activities associated with running an in-game casino are potentially significant violations of our policies.
Long story short - it's a really bad idea to try running an in-game casino, and we'd counsel against it. Please do not be surprised if, despite a lack of policy on the casinos themselves, that other account actions result from associated activities, including scamming.
There are better ways to turn a profit and entertain oneself in-game.