Perhaps "free speech absolutism" isn't quite the right framing here, but more "First Amendment absolutism," with all the known bounds and checks (defamation, libel, incitement to violence). It does give a US-centric bias, but may better convey the meaning and intent.

"Go lynch this man" is speech, but is not protected under the First Amendment. And the First Amendment gives much broader protection than most countries' legal systems do.