Can "free speech" be limited by ideology?

although it might seem counterintuitive I believe that only free speech can prevent the spreading of destructive and regressive ideologies while trying to censor them forces them into the shadow where they develop amongst its believers, unchecked and without constructive criticism. a funny example would be the KKK. once feared because they gathered in secret and developed into a myth surrounding their power and influence, the KKK lost its feathers when they started getting invited to talk shows on TV and looked completely ridiculous. in this way, when I personally have a debate or argument with someone, I let them speak first and make sure they have put all their arguments on the table, then I proceed to expose and dissolve all their arguments one by one until nothing is left. either that or I find myself unable to do so which means I might have to reconsider what I think in the light of new information. in respectful confrontation of ideas the more solid and sound ideas will be the ones to survive.