Unfortunately reality has a well-known liberal bias. Let's not mistake disinterest and impartiality for unquestioning support of "all sides".
The intent was to say that there is more to this than "platforms for diverse opinions ... censoring those they disagree with".
Regardless of their agreement, if they just censor those that are false they will appear to have a liberal bias. This is reportedly what scared Facebook away from dealing with fake, mostly right-wing, propaganda on their platform.
At some point you have to choose whose free speech you value more. Reddit has made some small attempts to stop the harassment, which in turn has made Reddit somewhat more diverse. Because misogyny has become a little less prevalent, I'm seeing more women on the site.
Free speech, as far as internet forums go, is not a black and white issue.