I think that good ideas should over power bad ideas. This doesn't mean that bad ideas should be censored. When it comes to things like racism (something I have and likely will continue to face) I prefer uncensored people as then I know where I stand. I can have had great discussions with people who have some very bad ideas and perhaps I have been able to make them reconsider. When they feel they must hide, we get the false sense that the bad idea doesn't exist.
Holocaust deniers, flat-earthers, what ever it is, these people should be able to voice opinions too.