There is an ongoing conversation about liberals' fear of dissent, mostly coming from writers who already have a large platform and are in no real danger of losing it. For those who don't -- smaller bloggers or writers without the backing of media or academia, who lack the proper credentials -- it's incredibly risky. Someone like Jon Chait or Michelle Goldberg can criticize their tribe, and while the backlash might sting, neither has had to surrender their liberal credentials for it.
I try to avoid "privilege" arguments because it's too easy and too formulaic to plot people on a spectrum of have and have not But, a privilege argument is apt here,. I'm not trying to deny the importance of those things, but they aren't the only things that form one's worldview. There's also a huge misconception that all of the criticism that the left is too concerned with political correctness or social engineering is coming from people of relative social power afraid of losing their status as good allies, and those with little standing welcome a sort of Orwellian control. No, there isn't a mob of over-sensitive marginalized identities sorting the good allies from the bad, and the risk of apostasy is always greater from someone coming from a marginalized group. (Ayaan Hirsi Ali's contentious relationship to American liberalism, for example.) I think this is getting a little lost in the discussion.
(Edit: I hadn't seen it since the update, but this discussion on Medium better illustrates some of points I was trying to (rather clumsily) make. )