As Aristotle apparently said "It is the mark of an educated mind to be able to entertain a thought without accepting it."
If we can't even discuss certain topics, if we can't even think things through, then we've entered the realm of thought police.
I ask this in a bit more depth here: https://news.ycombinator.com/item?id=14967029
I think the idea that we should suppress mere discussion of certain topics is very dangerous, and could lead society down a very dark path.
Let's not forget that things like interracial marriage, gay marriage and equality for women were once widely considered "abhorrent ideas".
Your comment was marked as "dead" and I just vouched for it, so does that count as not trying to censor every idea that disagrees with me? ;)
But I'm not convinced. There have been plenty of racists with arguments they consider rational. I think they are factually wrong, but surely the real point is "what you are saying is offensive and immoral" rather than try to argue that (eg) the costs associated with keeping black slaves is too much for the income the bring.
Furthermore, another way to damn a viewpoint is to associate it with poor arguments; or to strengthen a claim surround it with strong (or at least battle-tested/accepted/familiar) arguments. You should be happy that a true claim is discussed, creating stronger arguments, and making those better known; and that false claims are also discussed, explicitly demonstrating the poor arguments used to defend them.
Now, whether a poor/strong argument is recognised as such, that is another issue, and goes to the "rational literacy" of the general public, which certainly is an issue (on both sides).