Wiki - The paradox of tolerance states that if a society is tolerant without limit, its ability to be tolerant is eventually ceased or destroyed by the intolerant. Karl Popper described it as the seemingly self-contradictory idea that in order to maintain a tolerant society, the society must retain the right to be intolerant of intolerance.
You’re just doing the “all language is nihilism” thing.
Really, the logical issue is that the comic is taking a descriptive premise (tolerance of intolerance can, or perhaps is likely to beget intolerance) and forming an unqualified prescriptive message from it.
The reality of the matter is that all philosophy is local. Obviously descriptive ethics define prescriptive ethics, but rarely at a universal scale. “Tolerance can be dangerous,” “radical tolerance can be dangerous,” and “asbestos tolerance can be dangerous,” all express very different propositions. The better you can qualify the danger, and the more you can constrain the object, the better you can act on the statement.
You can argue that here, the comic does qualify its “bar” for intolerance with the nazi example. The semantic way of reading this is that the author is defending intolerance of Nazis, or some related abstraction. I therefore don’t think it is semantically correct to say that the author seeks to apply this ethos broadly.