If it happens due to reasons over which the pax has no control (rush bags, stuck in security etc.) and could not have predicted then it's hard for me to envision a threat situation under the circumstances. You may feel differently of course.
Try this one.
Passenger has "medical emergency" jus before departure, e.g. panic attack at last minute, plane departs sans pax.
30 mins later pax, recovered, leaves airport and disappears.
60 mins later "boom."