Free speech means free debate is possible. Free debate leads to a clearer understanding of the objective truth, and knowing the objective truth leads to justice, as long as people have morals (and most people still have morals, no matter what some may say). This has always been the 'liberal progressive' understanding, descending from thinkers like Locke, Voltaire and Mill. If some ideas still aren't heard in the free market of ideas, that just means it isn't free enough yet, and we should work to make it even freer (e.g. knock down the traditional barriers associated with independent publishing and content creation; abolish all taboos etc.)

It wasn't until the 1960s and later when the ideas of Marcuse (a disappointed old revisionist communist who was also scarred by fascism) and postmodern thinkers like Foucault (who essentially believed that everything is a social construct and had no respect for reality at all) corrupted progressive thought. These ideas were taken in eagerly by the 1968 activist generation (who were at that time immature enough to say 'don't trust anyone over 30', seriously), and led to the end of the New Deal Era and 30 years of conservatism as backlash. I think it's time for the failed experiment of the 'long 1968' to end, and for the original Enlightenment progressive vision to be championed again.