Heck no. I just wouldn't risk a set of JBL's on anything other than solid mounting. And, I'll just select a seat more toward the center of the room, if you don't mind!
Granted, I'm overly aware of the damage/fatigue and unexpected things that sonic vibrations can cause. I've seen main stacks walk-off position all by themselves. Impossible to believe considering it took a busload of roadies to get them positioned. Nowadays, EVERYTHING is tied down...