1. Regardless of whether the First Amendment legally compels it, I don't think that a healthy democracy can exist in a society that doesn't have tolerance for unpopular speech.
2. I disagree that citing free speech means that you are saying that "the most compelling thing you can say for your position is that it isn't literally illegal to express". What if you applied that same logic to other rights? For example, is Black Lives Matter saying that "the most you can say about black people is that they shouldn't be killed"? That would be ridiculous.
Basically, I think the comic misses the point: the First Amendment establishes the absolute minimum amount of tolerance for a society to not be authoritarian. It doesn't on it's own define the full extent of what constitutes the right to free speech in a healthy democracy.