The sticking part of the Sedition Act is this: "shall willfully utter, print, write, or publish any disloyal [...] language about the form of government of the United States". This is where it essentially makes any opinion against the government criminal, and that is unconstitutional. Where this was moderated in modern American law is that it was narrowed down to 'overthrowing'. It is quite a different and more specific matter than the broad word 'disloyal' which was used in that period to charge and imprison many persons who did not advocate anything more than "radical" (relative to the American mainstream) ideologies or systems of government. The legal prohibition of advocating the overthrow of the government is constitutional because such an overthrow would necessitate illegal means (violence, coercion), whereas the earlier prohibition of 'disloyal language' effectively bars otherwise constitutionally protected activities of organizing political movements and voting for change within the existing political framework.
How's that for indefensible, condescending AC shitbag?
Our safety, our liberty, depends upon preserving the Constitution of the United States as our fathers made it inviolate. The people of the United States are the rightful masters of both Congress and the courts, not to overthrow the Constitution, but to overthrow the men who pervert the Constitution. — Abraham Lincoln