Liberals have found an interesting rationalization that allows reconciling support for free speech with the need to censor ideas outside that threaten liberal ideology.

The trick is to claim that the total sum of valid ideas falls within the liberal ideology. All the ideas that are contrary are therefore fundamentally invalid, and thus can be treated simply as noise.

This is why liberals love the fake news and disinformation narrative so much. In their mind, they're not censoring valid ideas that are contrary to their own ideology, but are rather fighting against noise that has no fundamental value. Since these aren't valid ideas to begin with, liberals don't see censoring them as a form of censorship.