He's trying to argue that since companies own the platforms they can do anything they want on it even if it's illegal. So by that argument if you are in a private place that I own, I can gag you, rob you or even murder you with no consequence. It's not a slippery slope, its exactly what they are proposing. They are pushing their hand with the mass censorship but people aren't that brainwashed to see evil run amok.