The FD doors open out towards the cabin and the reinforced door and frame would make kicking it into the FD a very very difficult endeavor. You would need to kick it through the frame...I would pay to see anyone trying that successfully in a test. Passengers and crew would have plenty of time to act and restrain the offender or just club him over the head with a fire extinguisher.

I am very confident the doors will protect the FD...and if we are to have FAMs onboard, they are there to monitor the passengers, which is best done from either the rear, or at different locations throughout the cabin - not sitting in FC.