traditionally anti-social behavior meant fighting, keying cars, spraying graffitis etc. A kid with antisocial personality disorder can be a danger to other kids due to their reckless behavior.

social alienation caused by the internet and the social media usually manifests in asocial behavior like withdrawing from the society. in the recent years people have started calling this anti-social behavior, and they often get corrected by pedantic people such as myself.

what BBC meant by "anti-social" in this article is unclear.

They clearly mean the first definition. Ever since the Trump admin got editorial influence at the BBC, the remaining reporters have to be very careful to fly under the radar, or they will lose their jobs like their former colleagues did.

Re-read the reasons it enumerates for moving genuine social interactions to E2EE platforms, or at least 24 hour self-deleting posts.