If OP has any good statistics on the # of security incidents resulting in off-loading, it would be great if he posted them. Otherwise, this is just another media hype incident which seems pretty clear:

1. Must obey crewmember instructions.
2. Don't film or record crew members onboard (not only a safety & security issue, but there are plenty of whacko stalkers out there).

Seems like protocol was followed and this wasn't the FA's ultimate decision. Captain and law enforcement involved. While it's the Captain's final judgment, he apparently took advice from the cops too. Sounds like the decision to boot the other 8 had nothing to do with the FA.

The "animals" comment is uncalled for an unprofessional, but it has nothing to do with the security issues. Can't say the FA was wrong, just unprofessional.

Unlike a bus, you can't pull over to the curb at 35,000 feet and give someone the boot. Peoples' behavior tends not to improve with the passage of time.