Yes, a casino may kick out for this reason--or pretty much any other reason. A casino, as a private place of entertainment, has the same right that any other private business or store has to decide who to allow to patronize it or not; if someone is considered a risk or bad influence or undesirable, they can keep that person out. There are certain anti-discrimination laws that may act to prevent discrimination on certain bases--e.g. against a person's race, religion, age over 40, disability, or sex--but be aware that tribal casino's are exempt from a number of anti-discrimination laws, especially state (as opposed to federal) ones, due to tribes' status as semi-sovereign entitities.