In an open and democratic society, free speech is a value that is foundationally the core value that underpins everything. Free speech is there to protect the offensive and inappropriate... not civil discourse.
Supporting an environment where it's acceptable to respond to some perceived slight (which changes over time) with an crazy overreacting mob isn't OK in an open society ever. You're very sensitive to racist statements... how do you feel 10 years from when the "offensive statement of the day" is an anti-war statement? Or a statement offensive to a particular religious doctrine?
History is littered with people who do awful things while believing that they are righteous. Nobody in colonial Massachusetts was pro-witch. Nobody in 1950 America was pro-communist.