It's just not bombs that are a danger. You really don't want anyone to set the airplane on fire either, or start shooting people or holes into the fuselage.

AFAIK America has had plenty of shootings, and probably arson attacks too over that time period.

Other then https://en.wikipedia.org/wiki/China_Northern_Airlines_Flight... how often has anyone ever set fire to a plane (not counting bombs that caused fires). Is there even a single other example.

I agree on guns, but you can probably deal with that with much lower intensity security.