Doesn't have to be a pilot, any aviation person with the courage of his/her convictions can, and should, step up to the plate. But you had better be right.
Very true, but as you posted, you better be right.
In one case a deadheading FA was sitting next the overwing exit on the right side in a 727, an aircraft she had never served on. It was night and after landing the FE started the APU, which those of you that are not familiar with, the APU is in the main gear well with the APU exhaust next to the right side emergency exits over the wing on the 727.
As happens sometimes, the APU torched on start. The FA saw the flames flash by the window she was sitting next to. She assumed the wing was on fire, opened the emergeny exit and started screaming for all to evacuate the aircraft.
The cabin crew managed to stop any of the passengers from going though the exit, but had their hands full calming a buch of panicking passengers.