Most people use this cartoon as a way of perpetuating their personal agenda, however, this cartoon is missing the entire premise of the Paradox of Tolerance.
What Karl Popper is saying is that a civil society should not tolerate intolerance IF and ONLY IF it culminates into violence (i.e. violence begins to occur). Once the guns and knives are brandished, all bets are off, however, if someone is being an intolerant asshole and are spouting ridiculous shit, that doesn't mean they should be silenced. Intolerance or intolerant ideas should be challenged in a civil society by debate or conversation, not censorship.https://rationalwiki.org/wiki/Paradox_of_tolerance
So, uh, Karl Popper was for free speech, just not violence. Too bad people misinterpret his ideas, though.