I don't have the original post by Zinj to refer to, darn!
It seemed at one point during this picket...: http://www.xenutv.com/originals/hollywood.htm
...That the Security suddenly realized it would not be a good idea to incite a riot. My guess is that it was John Travolta himself, and not Security, that decided a mob action would not be a good idea.
Now I've looked at the above film clip, I can't be sure, be it seemed to me that there were Scientologists mixed in with the fans. Having been a 10+ year member of scientology, I recognize a lot of them when I see them.
Assuming a mob action had occurred, and if the picketers had been harmed, the media would have had to report that fans of John Travolta, and some of his friends in the Church, had beaten up some picketers at an opening event.
Even if the newspapers, out of professional courtesy, or out of fear, did not report properly on the incident, the word would still get out among the little people. Do not talk bad about scientology around John Travolta, the scientologists will beat you up.
There will be more pickets around John Travolta, and possibly Tom Cruise. Gentlemen, you would do well to make sure that no riots occur, that nobody picketing you gets hurt. If it happens, besides the fans, I assure you, scientologists will have been among the guilty, among the rioting mob.
Besides, the official PR line is that Scientology endorses Free Speech. In public it is a good idea to at least pretend this.
So VWD John Travolta, nobody was hurt.