It means there are Facebook pages/groups coordinating their followers to mass report posts or persons deemed "reactionary". These pages/groups mostly held pro-government viewpoints, although I can't comment on whether they have direct affiliation with the government or not. From what I've seen, many Facebook profiles gets locked after such campaigns. I assume a profile is automatically locked when the reports reach a certain threshold, and it can be very difficult to get it unlocked, since you need to contact Facebook directly.

From the article itself:

> Private groups filled with government partisans coordinate takedown campaigns — or worse — against any views deemed “reactionary” by the Vietnamese state, [...]

> The Intercept was able to gain access to one such closed-door Vietnamese censorship brigade, named “E47,” where it’s obvious, through Facebook’s apparent indifference, that the company has failed its users terribly.