<<So the only chance for people on board to survive is to keep cockpit clean, and gun in skilled hands can help this a lot.>>
I would respectfully suggest that that the ex-marine/air force/navy trained pilot is no more qualified to handle a firearm on the FD than the average joe passenger, full stop.
Do 'they' think so?
Of course these types do.
Otherwise, they would be advocating a more reasonable approach.
Cowboys never are deterred, just careless.
Same for ex-marine/navy/airforce...misinformed all, with regards to firearms on the FD.