The next step isn't "forced farm labor," that would indeed be a non-sequitur. A most likely next step is putting someone in jail over a tweet (already happening in the United Kingdom). It takes three or four more steps to get to forced farm labor.
People have been put in jail in the US for the equivalent of a tweet, but it doesn’t prove your point. The freedom of speech does not guarantee an individual freedom from the consequences of that speech. There is established jurisprudence to allow such prosecutions.
And no, being jailed for anything you can name does not mean we are on a path to following the USSR (or any similar trajectory). The problem with allegations of “slippery slope” is that it discounts that the US and UK have legal tools to challenge bad prosecutions and bad legislation. The courts have the ability to check the prosecution and juries have the ability to reject bad prosecutions (used infrequently, but importantly when the US government went after Dan Ellsberg)
Seriously asking: How can putting someone in jail over a tweet be closer to forced farm labor when the united states already has forced farm labor (see below for link)? How can we simultaneously be approaching something and also already there?