That a monopoly must play by different rules. As he says in the video, if a restaurant wants to charge him 5x the price of a meal because he's wearing a MAGA hat, he may do that, because a single restaurant is not a monopoly, but that if the electric company were to discriminate against you for your political beliefs, that is different.
Since these social media sources are essentially monopolies - even TV shows use "Google" as a verb meaning, look it up - they're monopolies and as such, may not do what they've been proven to do - discriminate against views they don't like.