I think, that before the muslim attacks on America (I refuse to write n-nn), airlines usually treated such incidents as possible hijackings and it was thought the best way was to just let things play out.
After we seated ourselves on the plane, airport officials came on board with a bomb sniffing dog and walked up and down the aisle then left the plane while escorting the guy off.
Don't know what it was all about and soon forgot about it........