I don't think it's about being murdered. There are very real, non-lethal consequences to writing certain uncomfortable opinions. Just having one's name attached to controversial articles, tweets and posts would be enough for some employers to think "nope, not worth the effort / PR hit" and not hire that person.

E.g. I have written a bunch of outlandish stuff in my comment history, and some of it would cause people a lot of offense. Enough for them to want to call my employer out of some motivation and escalate to some sort of public/twitter witch hunt. But I promise you, I am not a bad person, and would not hurt a fly. That is the part that's missing here. Reasonable, innocent people are potentially being treated as if they're inciting violence.