For fuck's sake Larry you are like a goddamn puppet with an Archie Bunker tape in his mouth. SOME liberals and conservatives are unrelenting advocates of individual liberty and free speech. SOME liberals and conservatives are not. If you want examples, I can give you plenty, which will just highlight the continuing decline of the intelligence of people who get force fed Fox News all day.
Keith, you asked a serious question, I'll try to answer.
As a citizen in the US, your free speech rights attach to your political writings of almost any sort, the distribution of the same, and your political speech in certain contexts, typically those deemed to be public forums. Meaning that in a purely private context, yes, speech in the US can be regulated. Additionally, as a side note, commercial speech gets less protection, but that is a different category altogether not pertinent to this example.
Here, the fairgrounds would almost assuredly be deemed a public forum so if private citizen wanted to do what these guys did, probably protected. Almost certainly so.
The rub here is that the actor -- the one engaging in speech - is the government itself and so it's really not a private citizen seeking protection of the 1st. It's more like a corporation deciding if it wants its employees expressing themselves a certain way.
And that I agree with. A state government making fun of the President, whether Republican or Democrat, isn't appropriate in my view. Private fair? Have at it.