We have several Supreme Court decisions that can help answer this question. First of all, misinformation was established to be protected speech in NYTimes vs Sullivan, where the SCOTUS unanimously found that the New York Times was within its rights to publish an advertisement containing factual inaccuracies[1].
Brandenburg v Ohio (also unanimous[2]) explicitly established the "imminent lawless action" test as overriding the "clear and present danger" test; which was further reinforced by Hess v Indiana in which the court found that Hess's words were protected by the First Amendment because his speech amounted to "nothing more than the advocacy of illegal action at some indefinite future time"; i.e. failing the "imminence" portion of the "imminent lawless action" test [3].
> While it's not the best, people are familiar with it. The replacement is certainly more accurate.
The entire point is that what people are familiar with is incorrect and should no longer be considered a valid argument. In fact, the irony of this logic is that one could argue that advocating for limiting speech by falsely citing an overturned precedent as currently relevant is itself misinformation that can be legally regulated even under the First Amendment; we would both agree that that is nonsense.
[1] https://en.wikipedia.org/wiki/New_York_Times_Co._v._Sullivan