They need to recall that no guns, nor even swords or knives, (unless you consider a boxcutter a knife, which it may technically be) were used on 9-11-2001, yet around 3000 people died.
Four guns in the right hands could have prevented those deaths, but the federal government in it's infinite (lack of) wisdom, forbade those "right hands" from having guns. Even now they continue to forbid it, unless those "hands" are those of volunteer Federal law enforcement officers (known as Federal Flight Deck Officers. (Wouldn't want to legitimize the notion that mere citizens could be armed in order to defend themselves and others, now would they?) See also ALPA who are not happy about many aspects of the FFDO program.