This is pretty hyperbolic. Somebody who was "moderate" in 1995 could be considered left-leaning or right-leaning today, depending on their specific politics, and in fact, without any specific context like "internet free speech", I would think a majority of them would be considered more left-leaning on average today. And even if that isn't true, the alt-right is a pretty specific flavor of hate-motivated shitposters, not just "people who are heavily right-leaning".