Would you want to unbuckle to stop somebody crazy fiddling with the door handle? The flight attendant should be interfering, including violently if needed. They might need a legal permit to do so and some police training.
There will be many more airline passengers from third world countries in general in the future so its about time to think about better dealing with first timers, scared, uneducated and unable to read anything passengers on board aside from this person who felt "scared" and panicked.