Offered not as legal advice, but as the basis for your own investigation into how First Amendment speech rights interact with Federal criminal statutes:
Seditious conspiracy is a federal crime under Title 18 US Code Section 2384. It states:
“If two or more persons in any State or Territory, or in any place subject to the jurisdiction of the United States, conspire to overthrow, put down, or to destroy by force the Government of the United States, or to levy war against them, or to oppose by force the authority thereof, or by force to prevent, hinder, or delay the execution of any law of the United States, or by force to seize, take, or possess any property of the United States contrary to the authority thereof, they shall each be fined under this title or imprisoned not more than twenty years, or both.”
Additionally, Title 18 US Code Section 2385 makes it a crime to advocate overthrowing of the government, and Title 18 US Code Section 2383 makes assisting, inciting, or engaging in rebellion/insurrection a crime, as well.
Most of the cases interpreting the seditious conspiracy statute date from the World War I era, but there are a couple of recent cases involving purported Islamic terrorism, in which they had engaged in training and had exhorted people to make war on the US.
(Additional legal research resources available at Cornell Law Library)
If you don't think the Bad People will use every tool at their disposal to crush and intimidate their political opponents, you don't know your enemy.
Why do you think the Lib press has been hyperventilating about the April 19th events?
It's called battlespace preparation, and any American who isn't prudent in how they phrase their opposition to the collectivist hordes will learn some hard lessons.
Watch yourselves, but remember also:
Audentes fortuna iuvat.