But the point in that post is this "goto example" is actually an example of the vague rationalizations used in attempts to censor speech. It covers two pillars of free speech exceptions which are both controversial - incitement(the case where the phrase came from), which Brandenburg vs Ohio narrowed significantly, and false statement of fact, which is very controversial, with decisions like Sullivan protecting newspapers from almost any liability vs the government.

The problem with almost all of the exceptions on freedom of speech is that they're all meant to be just that, exceptions in the most extreme of cases, and none of them are without controversy and tons of reinterpretation. Handwaving them away with the simplistic "falsely shouting fire in a crowded theater" does not do any of them justice.