Isn’t this a slippery slope argument?
Reddit has already shown that they had the capability and the will to edit users posts, not just removing them. Reddit and other social sites already uses all sorts of algorithms to move content they want to the top and to bury content they don't want. Companies don't want negative PR about themselves or their products. Companies advertising on Reddit are Reddit's actual customers.
You put those facts together and being afraid of Reddit eventually censoring posts critical of customers doesn't seem like fallacious thinking.
You don't throw a chicken into a cage with a starving tiger and call it a slippery slope to say that the chicken is going to get eaten
This is a lie. Hate speech is not illegal, and the SCOTUS has explicitly made this clear.
To not have an understanding of the critical importance for private individuals to speak freely shows an extraordinary lack of knowledge of history, for one. And you declare you are an attorney in your HN "about" page?
They're the same concept. And that concept is also in physics. "Things in motion tend to stay in motion unless acted on by an external force".
As an aside, there is something called the "fallacy fallacy" wherein pointing out a fallacy in someone else's argument doesn't necessarily mean that the argument's conclusion is false.
With that said, I'm not making an assessment of the above poster's reasoning.