Security is not going to monitor foul language nor should they. The job they are performing is keeping people physically safe. Policing abstract things like foul language isn’t appropriate, especially since there is not written policy outlining what word aren’t allowed to be said and if they did have such a policy, their comedians would need to vastly alter their sets.
The only requirement for the serenity area is that people be adults. Nothing about restricting language, monitoring volume, or limiting behavior.