I am actually shocked from reading this thread. The initial post made sense, the man who posted the sign was not only in the right, but would have my business in a heartbeat, it's the defending the "Stupid People" that blew me away.
If your kid is misbehaving in a place where people are paying to do something, and ruining their night, you should have to pay for their meals/movie/whatever. If you don't like it, either control your children or LEAVE. This should be law. I have a child, she's never done any of the things listed under the initial post because the one time she started acting up (It was in a movie theater) I immediately took her out, sat in the car with her, and waited. I tried to take her back in and she acted up again, we spent the rest of the movie in the car waiting for mom to finish. I didn't like it, but too bad, it worked. She was 4 and we never had to do anything like that again. Being a parent is hard sometimes because you HAVE to teach your kid what is and is not ok to do, and sometimes it inconveniences you. WAHH. Don't have kids if you can't be a parent. It's not your right to allow your spawn to screw up everyone elses night so you can ignore them and "relax". This is an Evil attitude, pure selfish Evil.
Also the idea that posting a sign asking kids (or anyone for that matter) to behave is Discrimination, is insanity. It shows a complete loss of touch with reality to think this. Only a lawyer could argue that asking people to behave is discrimination against those who want to misbehave. Of course I'd argue something that stupid for 150 an hour, and drag it out for years, but that's beside the point.