Technically they could enforce Texas' criminal statutes on public lewdness and use them as a basis to expell these persons from the park. I suspect that Florida has similar laws that would permit Disney to do the same thing.
I'm not a lawyer, but I would expect your statement to be true. As a Texan, there are certain forms of behavior I expect in a public establishment; and (to the best of my knowledge) this is not arbitrarily enforced. If the rules are broken, it is incumbent upon the park to either eject the violator, or bring charges against him/her. To anything less would be to encourage this behavior and be seen as promoting it. Given the relatively large sum of capitol Six Flags invests in maintaining a safe and fun family orientated image; I would expect that your assumptions would be true.