But it's that silence which deceives the user into thinking that the message never arriving is a technical malfunction and not intentional censoring. How many times, do you think the user would see the censoring message and be cool with it? Maybe once or twice, then they will stop using FB likely forever and tell all their friends. But does FB want that? Hell no, they want to retain the user for data collection and ad showing purposes. So how about just not showing the censoring message, make the user believe there was just a technical glitch and not insidious shadowbanning?

I think this "bug" is intentional and done for plausible deniability in case of a lawsuit: "See, there is transparence. It was just a bug in the code. Human error."