
Might not have helped much.
How much metal is in a razor blade to set off a metal detector? You could hide a razor blade in your pocket. For that matter, there are other things that could be used like knives that wouldn't be detected except by a really thorough search.
From the accounts that are coming out, these guys were armed with some *really* crude weapons, not requiring any inside help at all. Razor blades stuck in plastic handles? And the passengers just sat around while they started cutting throats?
That no man should scruple, or hesitate a moment to use arms in defense of so valuable a blessing [as freedom], on which all the good and evil of life depends, is clearly my opinion; yet arms ... should be the last resource. - George Washington