Torrent links are a viral vector and I'd expect them to be censored for the same reason the "hot pics" site would be censored... Potential compromise of user machines.
I'd be interested in what anarchist propaganda has been censored. Anecdotally, I see a ton of it on FB (a side-effect of being friends with anarchists), but I wouldn't be surprised if some things get dropped.
I've gotten smacked for sharing nudity (including, hilariously, reshares of my own Facebook posts from the past) and after January 6th, the service got very skittish about talk of violence and government (for I think obvious reasons... One of the few things that could end the party for Zuckerberg would be landing in prison for the very ambiguous charge "aiding sedition"). I have no doubt they engage in politically-related censorship... But we have no evidence that's what happened here, because (like any large public-facing messaging service that doesn't have a "user beware" attitude) they have those systems anyway for dealing with scammers and trolls.
