Can a casino kick you out for talking to other patrons?

Sort of a legal, and complicated question but maybe some people here will have some good insight to help. But say you're at a casino and you see a person watching right behind the person playing. Can you go up to the person playing and let them know that the person has been watching them for 45 minutes without playing any game of their own or is that some kind of issue? I'm asking because a friend of mine got into trouble with security for doing this, and I'm not so sure that security didn't break a law or something.

Can a casino kick you out for talking to other patrons?
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