The way you've phrased that makes it sound as though Facebook were trying to hide the actions they took to facilitate things, which I think is a miscommunication.
People on the Fediverse get high and mighty about the Myanmar incident but in a Fediverse world the Myanmar government would have run the big instance in their language and would have defederated anyone who tried to stop them, alternately outsiders could have defederated but then they wouldn't have any influence.
Fediverse folks could have refused to run a server to support genocide but there is no way they could stop their software from supporting genocide. A centralized system like Facebook does have more control and more responsibility but when they took that responsibility later on Myanmar kicked them out
https://apnews.com/article/myanmar-censorship-virtual-privat...
https://www.amnesty.org/en/latest/news/2022/09/myanmar-faceb...
https://time.com/5880118/myanmar-rohingya-genocide-facebook-...
https://www.theguardian.com/technology/2021/oct/07/facebooks...