Personally, I would not do anything to impede the Air Marshalls if they rose and identified themselves to take action.
If there is a firefight getting ready to happen, you can position yourself in the crossfire and cause the bad guys to get the advantage.
I would wait until the Air Marshalls took action, and then help them out if they need reinforcement, assistance, or whatever else they request.
Also helps you defend yourself from the inevitable lawsuit filed by terrorist sympathizers later on.