So, in eseence the tL;DR = FUD.
The Facebook rep I spoke with agreed that the company isn’t collecting the text of self-censored posts. But it’s certainly technologically possible, and it’s clear that Facebook is interested in the content of your self-censored posts. Das and Kramer’s article closes with the following: "we have arrived at a better understanding of how and where self-censorship manifests on social media; next, we will need to better understand what and why."