PR departments don’t want its aircrew on social media putting passengers in a headlock etc, especially if they are non violent, and just a nut job like this bloke. The cabin crew here obviously came to the conclusion that they were just dealing with a mental patient, they sat with him and just listened to his bull****. He did mention apparently that he was lying about having an explosive device, the authorities doing the intelligence work in the meantime wouldn’t be taking his word for that regardless, so the investigation would continue.
Some crew get a little too involved at times also. That Virgin pilot getting into a fight with the pax was a good example, sometimes it’s better to say nothing and just wait. I can assure you as I have seen, they will sack or demote you should you get on the wrong side of being involved.