Ranger one you asked to hear from cabin crew; what would we do under those circumstances in Milan?
Answering for myself only here.
Captain's decisions to be enforced as long as possible. When pax get out of hand and start getting aggressive I would inform the Captain that I was going to disarm the slide bars and open the doors.
Captain is God when it comes to decisions in-flight.
But this was a situation on the ground in a stationary AC, and I would follow my own common sense.
It's after all what the company pays me for doing.
Regarding the policing of pax, to a certain extent we have to do it, otherwise anarchy will break out on some flights.
But in far and away most cases handing the pax a "notice of violation" and telling him/her that (s)he will be met by local authorities upon landing, does the trick.
The best way in my experience is to come down like a ton of bricks in good time on those pax that obviously don't give a sh!t about the rules and the safety implications of same.
Since this goes against everything FA's are trained for, it's a new trick to learn for many of us. But it saves a load of hassle for everybody in the end.