Other examples of ridiculous ideas

32% of Democrats would support a state's right to secession (this was more common than among conservatives/Republicans).
59% of Democrat/Obama voters did not know which party controlled Congress in the 2008 elections (though of course a similar number of Republicans think Obama was in office when TARP was passed).
32% of Democrats believe Jews caused the financial crisis (again, more common than among Republicans)

Things like this. Ridiculous beliefs, even hateful and racist beliefs, are not limited to any one political side. And they are based, I think anyway, primarily on the fact that most people don't have a clue what is going on in the first place (as with the fact that most people don't know at any given time which party controls Congress, either house). What they are doing is applying a heuristic. It is a despicable heuristic that uses shortcuts of stereotypes and discrimination or racism and hate rather than a dispassionate analysis of the situation and its implications. But you're not going to short cut that heuristic by banning speech. Instead, you have to call people out for not paying attention, not giving a damn, not thinking too much, and so on. You can ask many American voters which party is (primarily) "pro-life" and they do not know the answer. And that is a contentious and controversial issue with a somewhat clear delineation. This says nothing about things like which party is in the pocket of "Wall Street bankers" or "pharmaceutical lobbies" and so on, and how people go about determining this. If people are not informed about the most basic political facts (who is on the Supreme Court, who controls Congress, who was in office when this passed, what is a candidates views on a particular issue, etc), and in general hold ridiculous, uninformed and sometimes hostile and pernicious beliefs about complex, but massively important to our lives and well-being, political issues like economics or foreign policy, I find it hard to believe that we're going to make much headway on little things like "Obama's a Muslim don't you know!" or "he was born in Kenya!" by worrying about what idiotic things are said to that effect and preventing people from saying them.